18 



February 10, 1852, 



W. Yarrell, Esq., in the Chair. 



The following papers were read : — 



1. Monograph of the Family BranchtpodidjE, a family 

 OF Crustaceans belonging to the Division Entomos- 

 traca, with a description of a new genus and species 



of the FAMILY, AND TWO NEW SPECIES BELONGING TO THE 



Family Limnadiad.e. By W. Baird, M.D., F.L.S. &c. 

 (Annulosa, PL XXII. XXIII.) 



Next to the Apodidce, the largest species of Entomostraca belong 

 to the fumilj Branckq)0(fidce. This family contains perhaps the most 

 beautiful animals of the division, elegant in form and graceful in 

 movement. The species are, geographically, widely extended, but 

 those as yet described are few in number. 



The Family may be thus characterized. 



Order Phyllopoda. 

 Family BranchipodidjE. 



Pedes branchiales, paribtis undecim ad novemdecim. Antennce dis- 

 similes, paribus duobus; par inferior in mare prehensilis. Oculi 

 duo, pedunculati. Corpus cylindricum, nudum, clypeo nulla 

 obtectum. 



The feet are all branchial, being formed entirely for breathing 

 with, and consist of 11 pairs, each pair -gradually enlarging in size as 

 they descend. They are in constant motion, and when so, present a 

 very beautiful wavy appearance. Like the Apodidee the animals of 

 this family swim upon their backs. The body consists of a considerable 

 number of segments, and is quite naked, having neither a shield- 

 shaped carapace like the Apodidee, nor a bivalve-shell-shaped cara- 

 pace like the other families of the Order PhijUopoda. The antennae 

 are dissimilar in appearance in the male and female. The superior 

 pair in both sexes are slender and filiform, but the inferior pair are 

 much larger in the male than in the female, and serve the purpose 

 of prehensile organs. The eyes are two in number, compound, oval- 

 shaped, and are placed upon considerable-sized peduncles. Like the 

 ApodidcB, the young Branchipodidce have only one eye, which dis- 

 appears in the process of moulting, but leaves a mark behind which 

 remains visible in the adult. 



The species included in this family are referable to five genera. 



Genus Branchipus, Schseffer. 



Corpus molle, cylindricum, segmentum caudale pinnis duobus ci- 

 liatis instructum. Pedes undecim. Antennce inferiores maris 

 magna, bi-articulatcB, cornibus similes, appendicibus duabus 

 filiformibus, antenniformibus, armatce. 



