some British Fossil Crustacea. 



333 



Common in the lower chalk of Cherry Hinton, near Cam- 

 bridge. 



{Col. University of Cambridge and Rev. T. Image.) 



(Fam. ThalassinidcE.) 



Meyeria (M'Coy), n. g. 



Gen. Char. Carapace strongly compressed laterally ; nuchal fur- 

 row very deep, V-shaped, the lateral portions nearly straight, 



Meyeria. 

 a. Side view. b. Carapace seen from above, c. Tail- flaps. 



meeting on the back at an acute angle considerably in front of 

 the middle, and extending to the lateral margins at a point 

 deeply notched by the abrupt narrowing of the front from 

 thence to the sharp rostrum : branchial furrow forming a nearly 

 straight, delicate, impressed line from near the lower ends of 

 the nuchal furrow to the middle of each side of the posterior 

 margin (never meeting on the midline of the back) ; portion 

 in front of the nuchal furrow with a few longitudinal, 

 strong, denticulated ridges, rest of carapace rough with small 

 pointed granules : abdomen semicylindrical, large, segments 

 sculptured with rows of granules, the ends of the second 

 joint dilated, quadrate, of the others subtrigonal, penultimate 

 joint a little longer than the fifth, carrying the two outer pair 

 of tail-flaps, which are strong, truncato-elliptical, with a mesial 

 ridge, ends fimbriated, the outer one on each side divided by 

 a transverse serrated suture about one-third from the end ; 

 middle tail-flap oblong, apex truncated, narrower than the 

 base ; legs slender, compressed, smooth, gradually diminish- 

 ing in size from the first, the lower edge minutely serrated. 



The Astacus ornatus (Phil.) is the type of this genus, which, 

 from the great compression of the carapace, size of the abdomen, 

 character and direction of the branchial furrows, &c, seems to 



