714 THE AMERICAN NATURALIST. [Vow. XXXIII. 
13. Carapax without median spine. : ‘ ; gepre 44 
14. Feet without exopodites ; fresh water . f ? NÆ I5 
14. Feet with exopodites ; marine pice 16 
15. Third pair of feet scarcely larger sii the anterior pairs Caridina 46 
16. Rostrum toothed, three anterior pairs of feet slender oe 47 
17. First pair of feet the larger, chelate . ALPHEINZE 18 
17. First and second ma of feet slender, the first not chelate 
(PANDALINE) Pandalus 65 
17. Second pair of feet the larger, both pairs chelate . PALÆMONINÆ 24 
18. Mandible with palpus . ; ‘ ; 
18. Mandible without palpus . ; i : ; : i -23 
19. Carpus of second pair annulate . ; i ; > a 
19. Carpus of second pair not annulate : ; : $ : az 
20. Rostrum very short or absent i ‘ > ` è ; = 2i 
20. Rostrum moderate or lon i . ; cae 
21. Eyestalks short, eyes hidden andes carapax . ‘ . Alpheus 48 
21. Eyestalks long, eyes free. ; - ‘ Ogyris 61 
22. First pair of feet short, second onde . ‘ ` . Hippolyte 59 
22. First and second pairs of feet subequal i : . Caridion 60 
23. Carpus of second pair triarticulate ‘ : .  Virbius 62 
23. Carpus of second pair five-articulate . i è : . Thor 64 
24. Mandibles without palpus . í ‘ ; gg 
24. Mandibles with palpus ; datent triflagellate : < Palemon 72 
25. Antennula biflagellate, one branch divided at the tip . : « 26 
25. Antennula triflagellate . . ; ` . 27 
26. Rostrum short; external masthead broad : ` . Pontonia 66 
26. Rostrum long, slender; external maxillipeds slender . Anchistia 67 
27. Rostrum toothed above only i ; ‘ . . Urocaris 71 
27. Rostrum toothed above and below : ` . Palæmonetes 68 
28. Posterior pair of feet not annulate ‘ P : «Penns 74 
28. Posterior pair of feet annulate . . i : . Stcyonia 76 
—, 
SYNOPSIS OF NORTH-AMERICAN CARIDEA. 
Family CRANGONID. First and second pairs of feet unequal. 
Sub-family CRANGONIN#. External maxillipeds pediform. 
G. Crangon Fabr. Eyes free; antennule biflagellate; posterior feet 
acuminate. 
29. 
Y 
ka 
34 
. Median a NA with vege or i spines ; ilaa ipni 
. Median carina two-spined 
—— He el sculptured; at least two spines in the median line ; 
om: n’ usually sculptured . 30 
ya not strongly snipredy one edian ial one Satara spine on 
either side * . 
tudinally keeled i « äl 
-n 
