REPORT ON THE ANOMURA. 101 



which the first two are of hirge size ; the appendages of the penultimate segment are large 

 and symmetrical in both sexes, forming with the telson a powerful swimming fin. 



The characters of this remarkable genus are extremely primitive, and it forms, as 

 has been pointed out by Professor A. Milne-Edwards, a connecting link between the 

 Thalassinids and the Pagurids ; at the same time there can be no doubt that its affinities 

 justify its position in the latter group. In Pylocheles we have as it were one of the first 

 downward steps in the series of degenerative changes which have transformed certain 

 Macrura into soft-tailed Hermit Crabs. It is closely allied to Pomatocheles,^ Miers, in 

 which, however, the carapace is narrower and more elongated, the chelae are operculiform, 

 and the fingers move in a distinctly horizontal plane. The only previously known 

 species is Pylocheles agassizii, A. Milne-Edwards, dredged by the "Blake" at a depth 

 of 200 fathoms off" Barbados, and found inhabiting an excavation in a piece of 

 sandstone, the mouth of which was closed by its chelae. It is doubtful whether the 

 Challenger species possessed any such habitation. 



Pylocheles spinosus, n. sp. (PL XI. fig. 1). 



Characters. — The anterior portion of the carapace is broad and moderately convex, 

 with a few slight inequalities towards the lateral surfaces and in front. The frontal 

 margin is slightly raised, the median process projects but slightly and is broad and 

 subacute, though tipped by a minute spinule ; the lateral processes are more prominent, 

 and their apices are acute. A transverse depression exists on the carapace a slight 

 distance behind the median ^^art of the frontal margin, and a few hairs are scattered 

 over the surface ; the posterior portion is less strongly calcified than the anterior, and 

 the cardiac area is triangular in shape ; the cervical groove is moderately shallow. 



The ocular peduncles are slightly compressed from above downwards, and extend 

 for about one-third of their length beyond the apices of the antennal peduncles, the 

 corneaB are slightly dilated, and semilunar in outline when viewed from above ; the 

 ophthalmic scales are of small size and their apices are acute. The antennal acicle does 

 not reach the middle of the last peduncular joint, and its apex is bidentate, a small 

 spinule is present on its anterior surface and another on the outer margin; the external 

 prolongation of the second joint is short and its apex bidentate, while an acute spinule 

 is present on the anterior surface of the same joint ; the terminal joint is slender and 

 subcylindrical ; the flagellum is about equal in length to the carapace, and its segments 

 are faintly pubescent. The terminal joint of the antennulax peduncle extends slightly 

 beyond the tip of the eye -stalk. 



The chelipedes are of equal size and similar appearance, with their terminal joints 



1 1 have provisionally included this genus in the section Laminibranchiata, hut so far as I know its j^ills have not 

 yet been esamineJ. 



