ANCEUS. 185 



of correctness, is the earliest stage in all crustaceous 

 life. The ova are proportionately very large, and the 

 parent retains the young after it has quitted the egg, 

 until the young animal is scarcely less than half the 

 length of the parent. M. Hesse has figured a speci- 

 men, in which he has represented all the larvae placed 

 within the ovi-pouch in a uniform manner, the head of 

 each being directed towards the centre of the pouch ; 

 this is not in accordance with our observations, as, of 

 the number of specimens that we have seen carrying 

 young, we have found all with the young creatures 

 variously placed, some with the head, others with the 

 tail, directed forwards or across. When the young quit 

 the care of the parent, nothing but a thin, transparent 

 skin remains, and the parent probably dies. 



The male differs from the female by the presence of a 

 remarkable pair of mandibles directed forwards ; fierce 

 and terrible organs of prehension they must be, but they 

 have always struck us as being organs that must be 

 valueless in assisting the animal in feeding. After we 

 had observed the structure of the oral organs of the 

 female, we directed our attention to those of the male. 

 In A. maocillaris,* on the under surface of the head, exists 

 a pair of large two-jointed plates, the basal being sub- 

 triangular and large, the other small and apical. From 

 its position and structure we consider this as the 

 representative of the hooked appendage in the young 

 animal, consequently the homologue of one of the pairs 

 of gnathopoda ; beneath this lies a pair of foot-jaws, in 

 form very closely resembling those of the adult female. 

 On removing these, we arrive at a crustaceous surface, 

 with a minute and apparently imperforated tubercle in 



* See the various details of the underside of the head and its organs 

 represented in p. 190. 



