.394.] MORTH-AMERICAN INVERTEBRATES. 821 
No 
3. Antennal scale absent, anterior feet monodacty] . > 8 
4. Hand of chelipeds large, broad, margins rounded, surtabec convex 
Stacine 5 
4. Hands of chelipeds prismatic, sides nearly straight (Nephropsine) 7 
5. Last thoracic segment not mobile; species marine . Homarus 17 
5. Last thoracic segment free from the rest ; fresh water è . 6 
6. Branchiz 17; species from the Atlantic water shed . Cambarus 22 
6. Branchiz 18; species from the Pacific slo ‘ Astacus 18 
7. Antennal scale absent; chelipeds densely sites . Nephropsis 23 
7. Antennal scale present; chelipeds naked and carinate Nephrops 24 
8. Body strongly depressed, lateral portions of carapax thin, margins 
inflexed; antenne lamellate . $ ; PRN I0 
8. Body and base of antennæ hba haol. Palinuridæ 9 
' Q, Antennæ oS touching at base; EERE i flagella and rostrum 
ts . alinurus 26 
9. Antennæ remote ; oaii flagella ong: rostrum absent 
Panulirus 25 
Io. Carapax elongate or sub-quadrate . : ; ; A : TI 
10. Carapax transverse, sides incised.! 
11. Rostrum well developed ; antennz ene: at the base; exopodite of 
external maxilliped with flagellum . . Scyllarus 27 
11. Rostrum very short; antenne remote; no flagella to exopodite of 
external maxillipeds ‘ - Arctus 28 
12. Branchie thoracic; external a A e iy p fin broad 
ebide? 13 
12. Branchiz thoracic ; external maxillipeds expanded operculiform ; caudal 
fin broad ‘ Callianasside 16 
13. Second pair of feet maonodacyie no Bp tbs, cake : . Gebia 34 
13. Second pair of feet didactyle; a small antennal scale i ‘= l4 
14. Eyes normally pigmented . : ` : A + li 
14. Eyes destitute of pigment and cornea : ; . Calocaris 37 
15. Hand of chelipeds regularly chelate . : . Arius 35 
15. Hand sub-chelate, the pollex folding on the BUS he . Naushonia 36 
16. Eyes sub-lamellate; antennular flagella longer than preceding joints ; 
second pair of feet chelate . . Callianassa 29 
16. Eyes cylindrical; antennular dagda aher oner than peduncle ; 
second pair of feet chelate . oo i . Callichirus 33 
1 Joacus parre (West Indies) and Evibacus princeps (Lower California) may 
occur within our limits. 
presence or absence of an antennal scale. 
grandimana. G. acanthochirus comes from Florida. The writer has seen no 
specimens. 
