376 



CRUSTACEA 



FAMILY 8. IDOTHEIDAE. 



Body more or less broad and flattened ; often elongate ; abdominal seg- 

 ments partially or completely fused ; uropods lateral, arching over and cov- 

 ering the other pleopods under the abdomen : about 90 species, 40 American. 



Key to the genera of Idotheidae here described : 



d Side of head cleft and extending beyond eyes 2. CHIBIDOTEA 



a z Side of head not extended in dorsal view. 

 &! Second antennae with a long flagellum ; abdomen of several segments. 



1. IDOTHEA 

 6 3 Second antennae without a long flagellum ; abdomen a single segment. 



c x Second antennae not much longer than head 3. EDOTEA 



c a Second antennae very much longer than head 4. ERICHSONELLA 



1. IDOTHEA Fabricius. Second antennae with a long flagellum and much 

 larger than the first; legs all alike; abdomen composed 

 of 3 complete and 1 partial segment : 8 American species. 

 I. baltica (Pallas) (Z. marina L. ; I. irrorata Say) 

 (Fig. 598). Length 20 mm.; width 7 mm.; color often 

 green, but very variable; abdomen ending in three projec- 

 tions: Nova Scotia to North Carolina; cosmopolitan; on 

 seaweed, in sand or at the surface; common. 



I. phosphorea Harger. Length 21 mm. ; width 7 mm. ; 

 color variable ; abdomen tapering to a point : coast of 

 New England, among rocks and seaweed. 



I. metallica Bosc (I. robusta Kroyer). Length 18 

 8 mm.; abdomen truncate: entire Atlantic coast; cosmo- 

 politan; often on floating seaweed. 



Fig. 598 



Idothea baltica 

 (Harger). 



mm.; width 



Fig. 599 



Fig. 600 



Fig. 601 



Fig. 599 Chiridotea cceca (Harger). Fig. 600 Edotea triloba (Harger). 

 Fig. 601 Erichsonella flliformis (Harger). 



2. CHIRIDOTEA Harger. Second antennae usually with a short fla- 

 gellum, sides of head cleft at the eye and extending beyond it; first 3 

 pairs of legs prehensile, last 4 pairs ambulatory; abdomen composed of 

 4 segments : 2 species. 



C. caeca (Say) (Fig. 599). Body ovate, with a long, pointed telson; 

 length 8 mm. ; width 4 mm. ; antennae of nearly equal length ; eyes small, 

 dorsally placed: Florida to Nova Scotia; at the surface or in the sand. 



