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. Thalassinide.) 
Meyeria (M‘Coy), n. g. 
Gen. Char. Carapace strongly compressed laterally ; nuchal fur- 
row very deep, V-shaped, the lateral portions nearly straight, 
SS ff 5) - ) 
~~ lll 
J, aa 
ee 
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 
m 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 ¢ail-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 
