some British Fossil Crustacea. 163 
obtuse oblong nodules (defined by a hollow along each side 
smoother than the rest of the carapace) ; branchial regions with 
four large tubercles, two before and two behind, the inner 
posterior one elongate obliquely backwards and outwards ; 
front four-lobed (including the prominent inner angle of the 
orbit) ; orbits large, the two lateral and the inferior angles pro- 
minent ; latero-anterior margin with about three tubercles or 
spines on each side, the posterior pair largest, placed at the 
greatest width of the carapace, and in a line with the sulcus 
separating the genital and cardiac regions; surface minutely 
and closely pitted; antenne as in Zantho (outer pair in the 
inner canthi of the orbits, inner pair in deep transverse fosse 
beneath the front) ; eyes on very short peduncles ; ¢azl of seven 
distinct pieces in both sexes ; first pair of feet forming robust, 
unequal chelee ; hand subecompressed, nodulated, with the upper 
and inner edge tuberculato-dentate ; fingers short, with few 
large obtuse teeth ; four hind pair moderate, subequal, slightly 
compressed, smooth. 
The Cancer Leachii (Desm.) may be looked on as the type of 
this genus; it was referred to Cancer or Zantho by Desmarest 
(Consid. sur les Crust. fos.) and to Cancer by Milne-Edwards 
(Suites & Buffon), from the want probably of good specimens. It 
is nearer to Zantho by its tuberculated carapace, few tubercles on 
the latero-anterior margins, and position of the external antennze 
at the mner canthi of the eyes, instead of between these and the 
front; but it differs in the great convexity of the carapace, and 
materially from both those genera in both sexes having seven 
separate joimts in the tail, showing in this a closer relationship 
with Pi/umnus, from which however the strong nodulation of the 
hind part of the carapace and its oval, vaulted form, as well as 
the quadrilobed front and great extent of the gastric region, di- 
stinguish it. I only know the genus from the London clay. 
Zanthopsis nodosa (M‘Coy). 
Sp. Char. Carapace about one-seventh wider than long, very gib- 
bous in the middle, sloping gradually to the sides, more rapidly 
towards the posterior margin, falling most rapidly and with an 
abrupt curve towards the fr ont ; anterior half broadly rounded, 
each antero-lateral margin with three large, obtusely rounded, 
nodular tubercles gradually diminishing towards the front ; 
tubercles of the branchial regions very prominent as large ob- 
tuse nodules ; gastric region tumid with a shallow depression 
along the middle ; genital region small, prominent, strongly 
divided by a wide transverse depression, posterior half most 
prominent, obscurely bilobed ; hollow space on each side of the 
mesial regional ridge remarkably smooth ; chele of the male 
rather larger than of the female, the upper ridge of the right 
PL 
