29S 



Descriptions of NK^^r Species of Soutk 



Australian Crustaceans. 



By A. ZiETz. 



[Read April 5 and May 3, 1887.J 



Plate XIV. 



Gryllopagurus lithodomus, gen. et sj). nov. 



The liermit crab about to be described differs so much from 

 any known sj^ecies that I have found it necessary to form a new 

 genus for its reception. The essential features may be defined 

 as follows: — Front, acute in the middle; ophthalmic segment 

 exposed, with a mobile scale ; eye-peduncles of moderate 

 length, rounded ; chelipedes of equal size ; fingers, on the tip, 

 s230on-excavated and black coloured ; first and second pair of 

 ambulatory limbs longest, with the end joint spiniform and 

 black ; third pair short, with the end-joint roundish, and with 

 a roundish rugosity ; fourth pair somewhat longer, with a 

 similar rugosity, and a shovel-like prolongation on the basal 

 joint or coxopodite ; abdomen soft, roundish, with indistinct 

 calcareous square plates and, only in the fcDiale, with four bifid 

 appendages on the left side of the abdomen ; the tail-fins narrow 

 and symmetrical. 



The only known species lives in self-made burrows in loose 

 stones. 



Gryllopagurus litliodomus is a short, robust animal found 

 near tide-mark in shallow water of St. Vincent Gulf. "When 

 attacked, the animal retires into its burrow, closing the same 

 perfectly with its chelipedes and first pair of ambulatory limbs, 

 which form when laid together a circular flat operculum when 

 viewed from above. The anterior portion of the crrapace, which 

 is marked by a deep cervical groove from the other regions, 

 shows the form of a heart, but its width is greater than its- 

 length. Ths pericardial cavity is marked by the branchio- 

 cardiae groove as a red shield. The branchial regions are of a 

 pale horny colour. The abdomen is soft, roundish, not spirally 

 coiled, with four indistinct broad transverse plates in both 

 sexes, and, in the female, only on the left side, with four bifid 

 appendages. The tail-fins consist of the telson, of which the 

 first part is divided by a cross' groove into two parts, of which 

 the posterior one is again divided by a longitudinal groove ; the 

 hind portion of the telson is bilobed. It possesses two pair of 

 tail-fins, of which the first is narrow, with its external part 

 directed backwards, and provided with a patch of small 

 papillae. The colour in spirit specimens is reddish, and especially 

 the limbs, are marked with large dark-red spots, some of 

 them encircling the limbs, forming bands. 



