32 ME. J. CAETER ON THE PALEONTOLOGY OE [Feb. 1898,^ 



unusually large ; cardiac lobe pentagonal, and slightly elevated. 

 A deep sulcus extends from the angles of the cardiac lobe and runs 

 parallel with the cervical sulcus. Epibranchial lobe piriform ; 

 inner half of the mesobranchial bilobed ; metabranchials large and 

 confluent posteriorly. The whole of the dorsal surface of the 

 carapace bears traces of depressed tubercles of moderate size. 

 Orbits small, round, four diameters apart. Abdomen of the female 

 seven-jointed (?) ; each segment trilobed, and the penultimate the 

 largest ; telson rather small. Limbs and other appendages ud- 

 determined. Length of carapace =16 mm. Width (metabranchial) 

 = 15 mm. 



Affinities. — This species has a general resemblance to M. lihinioides 

 of the London Clay, of which it is probably an ancestral form. It 

 is of smaller size, and may be further distinguished from that 

 species by the more delicate granulation of the surface, and by the 

 nodulated cephalic area ; the hepatic and branchial lobes are less 

 inflated, and the anterior branchial lobes relatively larger, conse- 

 quently the space between the cervical and transverse branchial 

 sulci is greater than in 3L lihinioides. The granulation of the 

 dorsal surface being much less distinctly marked than in M. lihi- 

 nioides renders the carapace comparatively smooth. 



Distrihution. — Cambridge Greensand. 



Genus Mitheacites, Gould. 



MiTHEACITES VECTENSIS, Gould. 



1859. Gould, Qiiart. Journ. Geol. Soc. vol. xv, p. 237 & figs. 1-3. 

 1863. Bell, Monogr. pt. ii, p. 1 & pi. i, figs. 2 & 3. 



Supplementary. — Orbits large, shallow, nearly round, twice their 

 diameter apart, directed forward and slightly upward. The eyes 

 are not lodged in the natural orbits, but rest in slight depressions 

 behind them. Antero-lateral margin with three or four obtuse 

 processes. Scapular area rather larger than the cephalic ; the 

 posterior border is slightly wider than the orbito-f rental. In the 

 early stages of growth the whole of the dorsal surface of the cara- 

 pace bears small granules, two or three diameters apart, which 

 become obsolete with age, as also do the areolar tubercles. The 

 disposition of the areolar tubercles is normal; the hepatic and 

 protogastric, together with one on the prolonged tongue of the 

 mesogastric, form a transverse row upon the cephalic area; the 

 base of the mesogastric lobe has one or three tubercles which soon 

 become obsolete ; the anterior branchials bear one, and the meta- 

 branchials four; the summits of these tubercles, when well- 

 preserved, are granular. The epigastric lobes are unusually large, 

 and obliquely elongated. 



The female abdomen is ovate, and the segments distinct ; telson 

 very small, triangular. Chelas equal in size ; meropodite with a 

 stout spine at the distal end ; length of propodite equal to half 

 the width of the carapace ; dorsum of hand finely granulated, 

 strongly convex ; palm flattened. Fingers rather shorter than the 



