CRUSTACEA. 
496 
TRIBE I.-OVALIA. 
With an oval body and transverse segments ; feet strong and 
of medium length ; those of the second and third segments im¬ 
perfect, with a long, cylindrical obtuse joint at their extremities, 
and each having an elongated vesicle at tbeir base. It has but 
one genus: 1. Cyamus. 
TRIBE II.-FILIFORMIA. 
Body long, linear ; segments longitudinal and narrow; feet 
long and slender; last portion of the upper antennae jointed. 
This tribe has three genera: viz. 2. Caprella ; 3. Proto ; 4. 
Leptomera. 
ORDER IV.—AMPHIPODA. 
Head separated from the segment which supports the second 
feet-jaws ; the post-abdomen provided with branchial and narrow 
elongated swimming appendages below, which are striated 
transversely, and with many articulations, or branchiae; mandi¬ 
bles having palpi. 
TRIBE I.-GAMMARINiE. 
Posterior extremity with conical, stylet-formed appendages, 
or without them.—Its genera are, 1. Cerapus; 2. Leucothoe ; 
3. Melita; 4. Amphithoe; 5. Dexamine; 6. Gammarus; 7. 
Pherusa; 8. Orcliestia; 9. Talitrus; 10. Atylus; II. Coro- 
phium ; 12. Podocerus; 13. Jassa; 14. Phronima. 
TRIBE II.-UROPTERA. 
With lateral appendages at the posterior extremity of the 
body, formed like leaflets, and serving as fins.—Its genera are 
15. Hiperia; 16. Phrosine. 
TRIBE III.-DECEMPEDES. 
Provided with ten feet only.—The genera are, 17. Typhis ; 
18. Anceus ; 19. Praniza. 
