CRUSTACEA. 
493 
TRIBE IV.-SCYLLARIDES. 
The peduncles of the lateral antennae formed like a flattened 
and horizontal crest. It has two genera: 48. Scyllarus, and 
49. Thenus. 
TRIBE V.-GALATHINiE. 
All the feet similar in form, but the two anterior which are 
didactyle. This tribe contains four genera: 50. Ergon; 51. 
Megalopa; 52. Galathea; and 53. Porcellana. 
TRIBE VI.-ASTACINiE. 
Four or six of the feet are didactyle; the exterior leaflet of 
the lateral appendage of the fin which terminates entire in some, 
and divided by a suture in others. The following are its genera: 
54. Thalassina; 55. Gebia; 56. Arius; 57. Callianassa. 
Genus 58.—NEPHROPS.— Leach. 
Generic Character. —External antennae having a produced 
scale at the apex of the first joint of their peduncle ; eyes reni- 
form, greatly thicker than the peduncle; six didactyle legs ; an¬ 
terior claws very long, angular and spinous. 
Nephrops Norvegicus. — The Norwegian Nephrops. 
Plate XCIII. fig- 3. 
Shell with scattered spines in front, the abdomen with hairy 
areolae. Inhabits the Northern seas. 
Genus 59—AST AC US.— Latreille. 
Generic Character. —With four unequal antennae set in a trans¬ 
verse line, the two intermediate shortest, and deeply cleft, the 
lateral ones simple and longer than the body ; the peduncle with 
scale-like teeth ; outer feet-jaws long, the two first joints provided 
with stiff bristly hairs, and small spines on the internal side; 
body oblong, subcylindrical; the shell with a protruding beak; 
tail with a fan-shaped fin, the lateral pieces divided in two ; six 
anterior legs didactyle, first pair very long and thick, with the 
band more or less tuberculous and spinous. 
2 s 
