Zoological Society. 217 



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 Branchipodid^e. 



Pedes branchiales, paribus undecim ad novemdecim. Antenna dis- 

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

 duo, pedunculati. Corpus cylindricum, nudum, clypeo nullo 

 ob tec turn. 



The feet are all branchial, being formed entirely for breathing 

 with, and consist of 1 1 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 Apodidce 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 Apodidce, nor a bivalve-shell-shaped cara- 

 pace like the other families of the Order Phyllopoda. 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 

 Apodidce, 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, Scheeffer. 



Corpus molle, cylindricum, seymentum caudale pinnis duubus ci- 

 liatis instructum. Pedes undecim. Antennae inferiores maris 

 maynce, bi-articulatce, cornibus similes, appcndicibus duabus 

 filiformibus, antenniformibus, armatce. 



The body is soft, cylindrical in shape, and is composed of twenty- 

 two segments. The head consists of two and the thorax of eleven, 

 each of which gives attachment to a pair of branchial feet. The ab- 

 domen consists of nine, the caudal segment dividing into two broad 

 flat appendages of some length, and plumose on their edges. The 

 inferior antennae, or " cephalic horns," in the male are large organs ; 

 they are composed of two articulations, which being cylindrical and 

 curved at the apex give an appearance of a pair of horns, and they 

 have springing from near their base a filiform appendage closely re- 

 sembling in appearance the superior antennae. The structure of these 

 inferior antennas, or cephalic horns as they are generally termed, and 

 the filiform appendage at their base, which are frequently described 

 as an additional pair of antennae, sufficiently distinguish the genus. 



Only two species of Branchipus have as yet been described: 



