I. '08. 60 



and two minute papillae on its internal aspect, quite close 

 to the wide hemispherical cornea. The antennular peduyicje 

 is very short, reaching to only about one-third the length 

 of the antenna! scale; the basal joint is longest, its 

 lateral f)i'ocess is not very acutely pointed anteriorly, and falls 

 short of the distal end of the segment. The antennal scale is 

 about five-sixths the length of the carapace in large specimens, 

 in smaller examples shorter; at its base it is about three 

 and a half times as long as wide, the lamellar portion being 

 strongly narrow^ed a^^ically. Externally it is slightly convex, 

 and terminates anteriorly in a strong spine. 



In the first maxillae the middle joint (basipodite) is 

 much broader than in A. purpurea; in the second the same 

 joint is also much broader than in that species, while the exo- 

 pod is narrower. The endopod of the first maxillipede is more 

 slender than in the allied form, w-ith its terminal segment 

 shorter, and the lamelliform exopod is very narrow apically. 

 The terminal joint of the endopod of the second maxillipede is 

 transversely articulated with the penultimate joint, not 

 obliquely as in A. purpurea. 



The third maxillipedes , w^hich bear long exopods, reach 

 rather beyond the middle of the antennal scale ; the penulti- 

 mate joint is scarcely more than half the length of the ulti- 

 mate. 



The five pairs of pereiopods all bear long exopods, decreas- 

 ing in size from before backwards. The first two pairs are 

 chelate and about equal in length — not quite reaching to the 

 middle of the ultimate joint of the outer maxillipedes. The 

 third and fourth pairs are much longer and when stretched 

 foTwards reach to considerably more than half the length of 

 the antennal scale. The merus is armed with numerous short 

 ventral spines and the propodus is at least three times the 

 length of the carpus ; the dactylus is very long — about two- 

 thirds the length of the propodus. In small specimens these 

 two pairs are only slightly longer than the others ; in examples 

 of 30-35 mm. they only reach as far forward as the first pair. 

 The fifth pair is very much shorter, and when stretched for- 

 wards scarcely reaches beyond the distal end of the carpus of 

 the fourth pair ; the dactylus is very much longer than in 

 A. purpurea, being nearly one-third the length of the pro- 

 podus. 



The pleopods show the usual structure ; those of the second 

 somite have two stylets at the base of the endopod in the male ; 

 one only in the female. The outer uropods are fully five and 

 a half times as long as wide. 



The eggs are very large, measuring about 3*2x2 mm. ; the 

 two ovigerous females examined were carrying twelve and 

 fourteen respectively. 



Luminous organs. 



Acanthephyra dehilis is the only Decapod so far known from 

 British and Irish waters which is possessed of photophores. 

 In life these are always associated with a deep blue pigment 



