EEPOET ON THE ANOMURA. 81 



Genus Tylaspis, Henderson. 

 Tijlaspis, Henderson, Narr. Chall. Exp., vol. i. p. 900, 1885. 



Carapace subcalcareous throughout, the anterior part strongly convex, the posterior 

 part (behind the cervical groove) of considerable breadth. Front with a prominent rostral 

 projection. Ocular peduncles moderately slender, the cornese scarcely dilated ; ophthalmic 

 scales absent. Antennules long. Antenna! acicle slender, the flagellum of moderate length. 

 Chelipedes slender and unequal, the right larger, fingers moving in a vertical plane and 

 calcareous at the tips. First two pairs of ambulatory limbs elongated and flattened, with 

 long slender dactyli ; the penultimate pair not chelate, and the last pair of small size. 

 Abdomen semi-extended and of comparatively small size, with two pairs of genital 

 appendages in the male ; the appendages of the penultimate segment slender and sub- 

 symmetrical. 



The form of the carapace alone suffices to distinguish Tylaspis from all other 

 Pagurids. It indeed presents some points of similarity to Ostraconotus, A. Milne- 

 Edwards, but the latter genus has the dactyli of the ambulatory limbs broad and flattened, 

 and a strikingly reduced abdomen. The single specimen came from the greatest depth 

 at which any Anomurous Crustacean was taken by the Challenger. The form of the 

 abdomen points to the species having occujoied some other dwelling-place than the 

 Gastropod shell usually selected by the soft-tailed Pagurids. 



Tylaspis anomala, Henderson (PI. VIII. fig. 5). 



Tylaspis anomala, Henderson, Narr, Chall. Exp., vol. i. p. 900, fig. 329, 1885. 



Characters. — The anterior portion of the carapace is subglobose, and provided with 

 several smooth rounded tubercles, of which two of large size are situated near the lateral 

 border, and two others of small size nearer the median fine. The anterior or frontal 

 border possesses a well-marked median rostrum, with the apex subacute and the upper 

 surface carinated ; a shght lateral projection is also present opposite the base of each 

 antennal peduncle. The posterior portion of the carapace is bounded anteriorly by the 

 deep and continuous cervical grooves ; the cardiac area is smooth and convex, distinctly 

 circumscribed, with its wall calcified ; the lateral or branchial region is of considerable 

 extent, the surface is slightly convex and slopes downwards, while the outer border is 

 convex, a longitudinal curved line divides it into two subequal areas covered everywhere 

 with small irregular elevations. The posterior border of the carapace has a well-defined 

 median concavity into which the first abdominal segment fits. The pterygostomial region 

 is sHghtly pubescent, and separated from the remainder of the carapace by a conspicuous 



groove. 



The ocular peduncles are somewhat slender, and the corneEe (which are deeply 



(ZOOL. CHALL. EXP. — PAKT LXIX. 1888.) Zzz 11 



