FOSSIL MALACOSTRACOUS CRUSTACEA. 



Genus — Cyphonotus, Carter, MS. 



Char. Gen. Testa subglobosa, latior quam longior, froiite triangular!, depresso, 

 incurvo, regionibus indistinctis, sulco nuchali triangulari, margiiic latcro-posteriore oblique 

 truiicato. Orbitre oblongaj, obliquae, supra Integra;. 



Species unica. Cyphoxotus incertus, niihi. Plate I, figs. 17 — 19. 



Descr. Carapace subglobose, the anterior margin forming nearly a semicircle, the 

 surface very even, covered with small granulations of various sizes ; the regions undefined ; 

 front triangular, bent downwards, and somewhat incurved at the apex ; latero-anterior 

 margin with an acute edge, and with four or five slight indentations ; latero-posterior 

 margin obliquely truncated and tubcrculated ; nuchal furrow forming an obtuse-angled 

 triangle ; a second, inconspicuous furrow extends transversely across the branchial regions 

 and between tlic gastric and cardiac, tending slightly forwards, so as nearly to meet the 

 nuchal furrow on the median line. Orbits oblong, oblique, open to the antennary fossae, 

 each partially divided by a very slight ridge, both on the margin and on the inner surface, 

 answering to the depression at the point where the eye joins its peduncle, when laid at 

 rest within the orbit. The upper margin of the orbit entire. 



Length of carapace, TS inch; breadth, TO inch. 



In Mr. Cunnington's collection, from the upper Greensand of South Wiltshire, and 

 in ;Mr. Carter's, from that of Cambridge. 



Obs. The peculiarities of this species, and the imperfect condition of the few 

 specimens hitherto found, are such as preclude any very certain ai)prcciation of its 

 affinities. The general prima facie aspect of the carapace would lead to the impression 

 that it belongs to the great group of the Cancerida;, and probably to that section of it of 

 which the genus Carpilius is the tpye ; but on a closer inspection the oblong form of the 

 orbits, with their partial division and oblique direction, the strongly depressed, incurved, 

 and triangular front, and some other characters, appear to forbid this view, and I am coni- 

 pcllcd to leave the question without any suggestion as to its true solution. 



A tolerably perfect carapace exists in Mr. Cunnington's collection from the upper 

 Greensand of the neighbourhood of llorningsham, in South Wiltshire, and several frag- 

 niciits from the Cambridge bed are in the possession of Mr. Carter. I have adopted the 

 generic name assigned to it by the latter gentleman in his MS. 



