Vol. 54.] THE DECAPOD CEITSTACEA OF EI^GLAND. 29^ 



J^ECROCAECINIIS WOODWAEDII, Bell. (PI. II, fig. 1.) 



1863. Bell, Monogr. pt. ii, p. 20 & pi. iv, figs. 1-3. 



Supplementary. — The small lateral teeth at the base of the 

 rostrum, mentioned by Bell, are not usually observable. The 

 antero-lateral border bears four or five small tubercles. The meso- 

 gastric lobe, in Gault specimens from Folkestone, bears a single 

 areolar tubercle, whereas, in Cambridge specimens, three or five 

 tubercles occur on this lobe. 



I have not met with examples of this species in which the chelae 

 are retained in situ ; but detached propodites of large size, which I 

 do not hesitate to regard as those of large specimens of N. Wood- 

 wardii, are frequently found in the Cambridge Greensand. Except 

 that they are twice or thrice larger, they precisely resemble the chelae 

 of N. BecTiei ; but I have no evidence that that species ever attains 

 so large a size as its congener. The two forms, however, have in all 

 other characters a close correspondence. In these large Cambridge 

 specimens the hand is robust, slightly compressed, and rather 

 longer than wide ; the dorsal surface bears a median series of three 

 equidistant tubercles, and a double row of smaller size on both 

 borders, frequently with a few others between these lateral rows ; 

 the palmar surface is very slightly convex ; the outer border of the 

 dactylopodite is flattened, and is bounded by a slender, slightly 

 denticulated ridge ; the dentary border is trenchant. 



The chela which Bell figured (pi. v, fig. 4) as that of N. Wood- 

 wardii certainly does not belong to that species, nor, I apprehend^ 

 do the other portions figured in the same plate (figs. 5, 6 & 7). The 

 chela is probably that of a new species. 



This species may be distinguished from N. Bechei by having a 

 large number of areolar tubercles — of which three or five are placed 

 upon the mesogastric lobe — and by having those on the cephalic 

 region placed in an almost straight transverse row, whereas in 

 N, Bechei they assume an undulating arrangement. Specimens 

 from the Chalk generally attain a considerably larger size than 

 those from the Gault or Greensand : a specimen in the Wood- 

 wardian Museum from the Chalk Marl of Cherry Hinton is more 

 than 60 mm. wide. Width of Gault specimens = 8 to 24 mm. 

 Width of Greensand specimens =25 to 50 mm. 



Distribution. — Tolerably abundant in the Gault of Folkestone and 

 in the Cambridge Greensand. Examples occur in the British and 

 Jermyn Street, Woodwardian, Folkestone, York, and other Museums. 



Genus Obithopsis, Carter. 



Orithopsis BoimETi, Carter. 



1868. Necrocarcinus tricarinatus, H. Woodward, Geol. Mag. p. 259 & pi. xiv, 

 fig. 4. 



1872. Orithopsis Bonneyi, J. Carter, Geol. Mag. p. 529 & pi. xiii, fig. 1. 



Description. — Carapace rather wider than long, considerably 



arched transversely, less so longitudinally ; dorsal surface minutely 



granulated, and still more minutely punctated. Orbito -frontal 



