400 History of British Entomostraca. 



Ill — The Natural History of the British Entomostraca. No. IV. 

 By William Baird, Surgeon H. C. S. &c. (Continued from p. 

 144.) 



In my papers in Vol. i. p. 514, and Vol. ii. p. 138, of this Ma- 

 gazine, I gave a history of the genera Cypris and Cythere, with a 

 list of all the species hitherto met with in this country. The next 

 two genera I shall notice are Daphnia and Lynceus, which vie with 

 any yet noticed, in variety and interest of details. In Latreille's 

 arrangement, they form the third group of his section Lophyropa, the 

 Cladocera, In M. Edward's work they will form the first order of 

 his legion Branchiopodes, the Cladoceres. Straus unites the Poly- 

 phemus, Daphnia, and Lynceus into one family, and calls it Daph- 

 nides. 



Order, Branchiopoda. — Section, Lophyropa. 

 Group, Cladocera. — Genus 1. Daphnia. II. Lynceus. 



1st Genus, Daphnia, 

 Bibliographical History. — Very great confusion exists amongst 

 the various authors who have noticed this genus, as regards the 

 species, and many are the errors in synonymy which they have com- 

 mitted. Indeed in this genus, as well as in the genus Cypris, very 

 little dependence can be placed either on the descriptions or figures 

 of many of the earlier authors. Swammerdam is the first author, 

 we know, that has taken notice of the Daphniss, though he mentions 

 that they had been observed before his time by Goedart, and named 

 by him " pons aquatiques." No mention is made by this author of 

 any insect resembling the Daphnia, in his work on the Metamor- 

 phosis of Insects, which is the only work of his I have seen, and 

 which Swammerdam quotes from liberally, in treating of the changes 

 which insects undergo ; and Straus says also, that he has never been 

 able to procure the work of Goedart, in which the notice of this 

 insect occurs. In his " Historia Insectorum Generalis," printed at 

 Utrecht in 1669, Swammerdam gives a pretty full description of a 

 species of Daphnia, which is evidently, from the indifferent figure 

 accompanying it, the Daphnia piilex. He calls it Pulex arboreus 

 or arborescens, the first part of which name has been retained, and 

 applied to this species by most authors who have written since his 

 time. His description is not very correct in some points, for he says 

 the beak is slender and pointed, and that it is by this sharp beak 



