CRUSTACEA 275 



describes them as a pair of maxillipeds with palps. Since in 

 Gnathia two thoracic segments are united with the head, 

 there must be originally two pairs of maxillipeds, and we may 

 here follow Dohrn's views and consider that in the adult 

 male the maxillae are wanting and the two pairs of maxillipeds 

 are much reduced. The pereion consists of five free segments, 

 each bearing a pair of walking legs, the two anterior segments 

 being separated from the three posterior by a constriction. 

 There is a sixth rudimentary segment, and a long median 

 penis projecting forwards between the fifth pair of walking 

 legs probably represents the two modified and united 

 appendages of this sixth segment. The " pleon " is consider- 

 ably narrower than the "pereion," and consists of six free 

 segments each with its pair of short paddle-like appendages. 



In the adult female the cephalon is much narrower than 

 in the male, and somewhat pointed in front, and both 

 mandibles and maxillaa are absent. Modified maxillipeds 

 similar to those of the male are present, but smaller. The 

 two first segments of the pereion are free, but the last three 

 are fused together and form a brood-pouch containing the 

 developing eggs. From this pouch the young are produced 

 alive and fully developed. 



From the absence of the mouth-parts in the female it may 

 be inferred that she does not feed, the eggs and young 

 developing at the expense of nourishment previously 

 acquired. It is fairly certain also that the male does not 

 use his large mandibles for feeding. According to Bate and 

 Westwood in the adult female there is neither mouth, 

 stomach, nor alimentary canal, but it is not stated that these 

 digestive organs are entirely absent in the male. Unfortu- 

 nately the act of copulation, so far as I can discover, has not 

 been observed or described, but I think in all probability the 

 enlarged mandibles of the male are used either to hold the 

 female or to fight with other males. Dohrn states that 



