22 FOSSIL MALACOSTRACOUS CRUSTACEA. 



Descr. Carapace depressed, suborbicular, granulated, with about sixteen moderate- 

 sized tubercles, the regions not very distinct ; the curved sculptured line between the 

 nieso- and uieta-branchial lobes strongly marked, and resembling im[)resscd letters ; a 

 distinct, but not very elevated, carina on the median line, extending the whole length of 

 the gastric region, and interrupting the nuchal furrow, and another carina on each 

 branchial region, extending longitudinally on the middle of the metabrancliial lobe, 

 strongly granulated ; the margin of J^he specimen described is much broken, so that we 

 are left to speculate in some measure upon the exact figure of the carapace ; but 

 following the line indicated by the portions which remain entire, it appears to be less 

 uniformly rounded than in Necrocarciniis W'oodwardii. The orbits have two fissures in 

 the superior margin, as in the other species. 



Length of the carapace, 1'4 inch; breadth, 1"G inch. 



From the upper Greensand of Cambridge and of Wiltshire ; it has also occurred in 

 that of Lyme Regis, in Dorsetshire. 



Ob>i. Specimens of this species occur in Mr. Carter's collection from the Cambridge 

 Greensand and in that of ^Ir. Cunnington from Wiltshire. But probably the earliest 

 notice of it is to be found in Sir Henry de la Beche's paper on " The Geology of the 

 South Coast of England," in the ' Transactions of the Geological Society,' read as early as 

 1S19. It is there mentioned only as "the back of a singular fossil crab," and as the only 

 one he had seen. There is an unmistakeablc figure of it,* although the teeth on the 

 anterior margin are represented as far more prominent and acute than any which I have 

 seen on actual specimens. 



The distinctions between this and either of the other species of the genus, whether 

 British or foreign, arc very obvious. The depressed carapace, the smaller and fewer 

 tubercles, and the distinct, although low, carina on the median line and on each branchial 

 region, are so striking that it cannot be mistaken even for N. IFoodwardii, which it 

 a[)proaches more nearly than N. Bechei. 



Orbkr—JKOMUFA. 



Famil//—nO'SlOLXDJE. 



Genus — Homoi-opsis, Carter, MS. 



Char. Gen. Testa longior cpiam latior, alta, (juadrilatcra, tuberculata, regionibus 

 distinctis, branchiali maxima triangulari. Orb'ilm approximatae, subrotundae, supra 

 unifissa! ; fossa antennarice ovales, transversae ; epistoma forte pentagonum. 



* 'Trans. Geol. Soc.,' 2nd ser., vol. i, pi. iii, fig. 1, p. -12. 



