XANTHILITES. 17 



to the conclusion tliat tliis is a distinct species. Its name, unispinosa, is, however, a very 

 incorrect one, for although the hindermost of the lateral processes is considerably larger 

 than the one before it, this is not more the case than in many specimens of X. bispinosa. 

 It has been obtained at Sheppey, and I believe also at Highgate, and exists in the 

 British Museum, in the collections of the University of Cambridge, of Mr. Bowerbank, 

 of Mr. WethereU, of Mr. H. Gould, and of ]\Ir. Searles Wood. 



Length of carapace, 1"7 inch; breadth, 2 inches. 



A somewhat mutilated specimen in Mr. Bowerbank's collection is considerably larger, 

 but of similar proportions. 



In Mr. Bowerbank's collection there is a specimen of a Xanthopsis which resembles 

 in its general form X. LeacJiii ; its proportions, with regard to height, length, and width, 

 are similar, the tubercles are nearly as prominent as in ordinary spechnens of that species ; 

 but instead of three rounded tubercles on the latero-anterior margin, there are two rather 

 sharp but short spines, the posterior being the larger. These spines differ fi'om those 

 of X. bispinosa in not being depressed, in being considerably shorter, and not in the 

 slightest degree reflexed. I beheve it to be a variety only of X. LeacJiii; but it appears 

 desirable to call attention to it, as it comes from Alum Bay, in the Isle of Wight, 

 a locality so remote from that in which the species just named is usually found. I have 

 given a figure of it,* for the sake of future identification. 



Genus — Xanthilites, miJu. 



Char. Gen. Testa paulo latior quam longior, margine latero-anteriore brevi, 

 quadridentato ; regionibus distinctis. Fossce antennarice obliquse. Antennae internee 

 articulo basali, una cum iUo antennarum externarum, hiatimi orbitae claudente. Fedes 

 antici magni, robusti, digitis acutis, fere inermibus ; reliqui subcyhndrici, laeves. Abdomen 

 MARIS ? rcEMiN^ cllipticum, articidis omnibus separatis. 



Sp. unica. Xanthilites Bowerbankii, mihi. Plate II, figs. 2 — 6. 



Descr. Carapace almost as long as it is broad ; nearly horizontal from side to side, 

 the anterior third considerably curved downwards ; the front somewhat projecting, 

 obscurely bilobed; latero-anterior margin very short, having four processes, of which 

 the anterior two are very short and somewhat quadi-atc, the posterior obtusely triangular 

 and more projecting ; latero-posterior margin very short, obliquely truncate ; posterior 

 margin with an elevated border, which is separated from the rest of the carapace 

 by a distinct groove ; regions very distinct, and coarsely granulated, the furrows rather 



* Plate I, fig. 10. 



3 



