22 ME. J. CAETEE OlS^ THE PALEONTOLOGY OP [Feb. 1 898, 



branchial process remarkably prominent ; postero-lateral margin 

 thick. Most of the areolar tubercles become more or less obliterated 

 in aged individuals. The normal regions are distinctly defined in 

 young specimens, but become gradually confluent as growth advances. 

 Epistome equilaterally triangular, granulated, larger than the 

 endostome. Female abdomen broadly lanceolate ; all the segments 

 distinct ; surface minutely punctate ; chelas rather small ; propodite 

 as long as the orbito- frontal margin is wide ; meropodite as long as 

 the carapace, slightly granulated and sulcated longitudinally ; car- 

 podite cuboid ; hand about twice as long as wide, oval in transverse 

 section ; fingers slender, as long as (or longer than) the hand. All 

 the ambulatory limbs are well-developed ; the m.eropodite is as long 

 as the carapace, angular, granulated, and spinulose on both borders. 

 Length of carapace = 8 to 25 mm. ; average adult size = 20 mm. 



BemarJcs. — Several obvious mistakes occur in Bell's description 

 of this species. It is one of the most variable of brachyurous forms. 

 • Specimens dififer considerably according to age, rendering specific 

 description exceptionally difficult ; the Gault examples at first sight 

 appear to difiPer much in general aspect — particularly old individuals 

 — from the Cambridge Greensand form; the difiPerence, however, 

 arises almost entirely from the degree to which the system of areolar 

 tubercles on the cephalic area and the processes upon the lateral 

 margin are developed. The carapace of a specimen in the British 

 Museum, from the Gault, near Aylesford (no. 51210), is nearly 

 even — the areolar tubercles and the prominences characteristic of 

 the species being so indistinctly expressed as to suggest that it may 

 be a distinct form. It would be of interest to examine other 

 examples from this locality. 



As usually found most specimens have a fracture on one or both 

 sides, extending from the orbit towards the posterior border, 

 probably the result of pressure upon the highly- vaulted carapace ; 

 not unfrequently the lateral portions are completely broken away^ 

 and the central portion only, showing the median lobes, is preserved. 

 Bell has alluded to the close resemblance of this species to Dromilites 

 Lamarckii, from the London Clay, which is very marked in old 

 individuals. 



Distribution. — Gault and Cambridge Greensand. Specimens are 

 in the British Museum, Museum of Practical Geology, Woodwardian 

 Museum, and my own collection. 



HOMOLOPSIS EEPEESSA, Sp. UOV. (PI. I, fig. 5.) 



Description. — Carapace approximately hexagonal in outline, flat- 

 tened dorsally. Rostral portion of the orbi to-frontal border prominent. 

 An undulating cervical sulcus crosses the carapace about midway 

 between the anterior and posterior borders. Most of the normal 

 cephalic regions are indistinctly defined ; those of the scapular area 

 are more distinct^ marked. The dorsal surface is minutely granu- 

 lated throughout, but the areolar tubercles are obsolete, except two 

 of small size, with granulated summits on the metagastric lobes. 

 The orbits are large, shallow depressions, with sharp irregular 



