Oithona is a planktonic crustacean genus found in marine, fresh water environments. Oithona has been described as the most abundant copepod in the world's oceans, it was first described by Baird in 1843 using the species Oithona plumifera as taxon type. The following species are recognized: Oithona aculeata Farran, 1913 Oithona alvarezi Lindberg, 1955 Oithona amazonica Burckhardt, 1913 Oithona aruensis Früchtl, 1923 Oithona atlantica Farran, 1908 Oithona attenuata Farran, 1913 Oithona australis Nishida, 1986 Oithona bjornbergae Ferrari F. D. & Bowman, 1980 Oithona bowmani Rocha C. E. F. 1986 Oithona brevicornis Giesbrecht, 1891 Oithona colcarva Bowman, 1975 Oithona cruralis Nishida, Tanaka & Omori, 1977 Oithona davisae Ferrari F. D. & Orsi, 1984 Oithona decipiens Farran, 1913 Oithona dissimilis Lindberg, 1940 Oithona erythrops Brady, 1915 Oithona fallax Farran, 1913 Oithona farrani Oithona flemingeri Oithona fonsecae Ferrari & Bowman, 1980 Oithona fragilis Nishida, 1979 Oithona frigida Giesbrecht, 1902 Oithona gessneri Kiefer, 1954 Oithona hamata Rosendorn, 1917 Oithona hebes Giesbrecht, 1891 Oithona horai Sewell, 1934 Oithona linearis Giesbrecht, 1891 Oithona longispina Nishida, Tanaka & Omori, 1977 Oithona minuta Scott T. 1894 Oithona minuta Krichagin, 1877 Oithona nana Giesbrecht, 1893 Oithona nishidai McKinnon, 2000 Oithona oswaldocruzi Oliveira, 1945 Oithona pacifica Oithona parvula Oithona plumifera Baird, 1843 Oithona pseudofrigida Rosendorn, 1917 Oithona pseudovivida Shuvalov, 1980 Oithona pulla Oithona robertsoni McKinnon, 2000 Oithona robusta Giesbrecht, 1891 Oithona rostralis Nishida, Tanaka & Omori, 1977 Oithona setigera Oithona similis Claus, 1866 Oithona simplex Farran, 1913 Oithona splendens Baird, 1843 Oithona tenuis Rosendorn, 1917 Oithona vivida Farran, 1913 Oithona wellershausi Ferrari F.

D. 1982 Oithona abbreviata Oithona alia accepted as Oithona rigida Giesbrecht, 1896 accepted as Dioithona rigida Oithona canhanhae Oliveira, 1945 accepted as Oithona hebes Giesbrecht, 1891 Oithona challengeri Brady, 1883 accepted as Oithona setigera Oithona helgolandica accepted as Oithona similis Claus, 1866 Oithona neotropica Herbst, 1967 accepted as Oithona oswaldocruzi Oliveira, 1945 Oithona oculata Farran, 1913 accepted as Dioithona oculata Oithona oligohalina Fonseca & Björnberg T. K. S. 1976 accepted as Oithona oswaldocruzi Oliveira, 1945 Oithona oraemaris Oliveira, 1946 accepted as Oithona hebes Giesbrecht, 1891 Oithona ovalis Herbst, 1955 accepted as Oithona hebes Giesbrecht, 1891 Oithona ovata Lindberg, 1950 accepted as Oithona attenuata Farran, 1913 Oithona pelagica Farran, 1908 accepted as Oithona setigera Oithona plumosa Lindberg, 1947 accepted as Oithona nana Giesbrecht, 1893 Oithona pygmaea Boeck, 1865 accepted as Oithona similis Claus, 1866 Oithona rigida Giesbrecht, 1896 accepted as Dioithona rigida Oithona sapucaiae Oliveira, 1945 accepted as Oithona hebes Giesbrecht, 1891 Oithona scriba accepted as Oithona plumifera Baird, 1843 Oithona sinensis Burckhardt, 1912 accepted as Limnoithona sinensis Oithona spinifrons Boeck, 1865 accepted as Oithona similis Claus, 1866 Oithona spinirostris Claus, 1863 accepted as Oithona setigera Oithona spinulosa Lindberg, 1950 accepted as Oithona brevicornis Giesbrecht, 1891 Oithona tropica Wolfenden, 1906 accepted as Oithona setigera

Frances Carr, Countess of Somerset, born Frances Howard, was an English noblewoman, the central figure in a famous scandal and murder during the reign of King James I. She was found guilty but spared execution, was pardoned by the King and released from the Tower of London in early 1622, she was born Frances Howard, the daughter of Lord Thomas Howard, his wife, the former Catherine Knyvet. Frances' father was the second son of Thomas Howard, 4th Duke of Norfolk, a wealthy and powerful nobleman during the late 16th and early 17th centuries, Margaret Audley, Duchess of Norfolk. Frances' maternal grandparents were Sir Henry Knyvet, of Charlton and Elizabeth Stumpe, she was the ten-times-great grandmother of the actress Celia Imrie. Lady Frances Howard was married at the age of 14 to the 13-year-old Robert Devereux, 3rd Earl of Essex; the marriage was a political union. Essex went on a European tour, when he returned Frances made every effort to avoid him, he was at the time ill with smallpox. She was at court and on 5 June 1610 danced as the "Nymph of Lee" representing the Essex River Lea in the masque Tethys' Festival.

She had fallen in love with Robert Carr, 1st Earl of Somerset. When she took the step of annulment, unable to represent herself, her father and her uncle, Henry Howard, Earl of Northampton, represented her and drew up the libel; the situation attracted public attention, was observed by those with "prurient minds". She claimed that she had made every attempt to be sexually compliant for her husband, that, through no fault of her own, she was still a virgin, she was examined by two midwives who found her hymen intact. It was rumoured at the time that Sir Thomas Monson's daughter was a substitute, possible because she had requested to be veiled during the examination "for modesty's sake"; the matter was a subject of mockery and ribald commentary throughout the court, including: This Dame was inspected but Fraud interjected A maid of more perfection Whom the midwives did handle whilest the knight held the candle O there was a clear inspection. In turn, Essex claimed that he was capable with other women, but was unable to consummate his marriage.

According to a friend, one morning he had stood up and lifted his nightshirt to show them his erection—proving, if nothing else, he was physically capable of arousal. When asked why only she caused his failing, he claimed that "she reviled him, miscalled him, terming him a cow, coward, beast." The idea of satanic involvement was considered by the judges and at one point it was proposed that Essex should go to Poland to see if he could be "unwitched". The annulment languished and would not have been granted if it were not for the king's intervention. James I of England granted the annulment on 25 September 1613. Frances married Somerset on 26 December 1613. Sir Thomas Overbury, a close friend and advisor of Somerset, had tried to advise Somerset not to marry Frances Howard, but the Howard family and their allies were powerful; the Howard faction persuaded the king to offer Overbury the post of Ambassador to Russia, knowing he would refuse in order to stay in England by Somerset's side. When he did so, the king viewed this as an insult and imprisoned Overbury in the Tower of London, where he died.

The annulment of Frances and Essex's marriage went through eleven days after Overbury's death, in September 1613, her marriage to Carr took place the following November. 18 months in the summer of 1615, a Yorkshire apothecary's assistant confessed on his deathbed that he had been paid £20 by the Countess of Essex to supply her with poisons for murdering Overbury. James I's Secretary of State, Sir Ralph Winwood, brought the accusations to the King's attention in September, James in turn urged his Privy Council to investigate the matter; the subsequent investigation and trial revealed that Frances had been surreptitiously poisoning Overbury for some time before his death, by smuggling jellies and tarts into his chamber tainted with white arsenic and other toxic compounds. The Lieutenant of the Tower, Gervase Helwys, admitted that he had received a confession from Overbury's keeper, Richard Weston, that he had been bribed by the Countess of Essex to administer the poison. Helwys intercepted the tainted sweets at one point and from on took the precaution of having Overbury's food prepared in his private kitchen, taking care to intercept any other food before it could reach Overbury.

However, for fear of the Countess of Essex's political influence, because his own patron was Frances' great uncle Henry Howard, 1st Earl of Northampton, he took no action against her. Frances succeeded in poisoning Overbury with a smuggled enema laced with mercury chloride. Frances and her husband were arrested for the murder in mid-October 1615; the trial revealed that Frances had supplied the poisoned enema to Richard Weston through an intermediary, Frances' waiting-woman and companion Mrs. Anne Turner. Helwys was tried as an accessory, his patron at Court, Sir Thomas Monson and imprisoned for involvement. Between mid-October and December 1615, Turner and the apothecary James Franklin, were all found guilty as accessories to murder and hanged. Monson twice had his trial delayed, in November and December 1615, before prosecution was dropped. Frances Somerset admitted her complicity in the crime.