82 J. R. KiNAHAN on the Britannic Species of 



Of these, five species are Britannic, all of which have occurred to me in the 

 Eastern Irish Seas. 



The exact position of the group has been a subject of dispute, M. Ed- 

 wardes placing it among the macrourous Decapoda ; Bell, and most subsequent 

 authors, among the Anomoura. AYith these last my own investigations would 

 lead me to concur, since the imperfect cheliform development of the fifth pair 

 of chelipeds (appendages of the fourteenth somite), conjoined with the depres- 

 sion of the body from above, is peculiar to and characteristic of Anomoura ; 

 for, with the exception of a curious crustacean described by Professor Bell as 

 allied to the Pinnotheridaa (and I suspect, had we more specimens, even this 

 will be found to be only an additional proof of the law), these are always found 

 to be accompanied by the peculiar arrangement of the sixth pair of pleopods, 

 which is characteristic of the group. 



Observations on the GalatheidiE alive, in the dredge and in the aquarium, 

 confirms this — anomourous aie they in all their actions. I have kept all the 

 British species, except nexa^ in the aquarium, and find that in confinement the 

 abdomen is carried closely folded up under the body ; and although in swim- 

 ming the animals progress by darts backwards in the same mode as Homarus, 

 yet their ordinary manner of progression is by ambulation, like other anomoura. 

 The submembraneous nature of the telson, and the great length of the external 

 maxillipeds, are also arguments in favour of their anomorous tendencies. 



HOMOLOGIES OF THE GROUP. 



Ocular, auditory antennal, and olfactory antennal, or first, second, and third 

 somites, only developed inferiorly, and completely concealed above by man- 

 dibular (fourth) somite, which alone forms carapace ; beneath a suture sepa- 

 rates from this a portion which probably belongs to the sixth somite (6 ?). 



The carapace is entirely made up superiorly of the fourth somite, and in all 

 the British species has its surface covered with a series of transverse raised 

 ridges, which are divided into two sets : a principal, the anterior borders late- 

 rally developed into teeth, the posterior smooth on their edges ; and a se- 

 condary, which is generally edentulous. It is flattened from above horizon- 

 tally, and produced anteriorly as a toothed rostrum, in the same plane as the 



