472 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Upper surface of merus and manus of cheliped dilated toward mid- 

 dle ; margins with teeth similar to those of carapace. Fingers meeting 

 without gape, tips crossing ; prehensile edge of pollex knifelike. Crests of 

 walking legs denticulate. (Redescription based on figures of the type and 

 Gulf of California specimens of both sexes.) 



Closely allied to C. concava, from which it is distinguished by its 

 greater breadth (1.6 times its length), narrower rostrum, rounder 

 posterolateral angles, greater extent of the closed fissures between the 

 marginal teeth. (Rathbun) 



Material examined: 71 specimens from 21 stations. (See Table 104) 

 From Santa Maria Bay, west coast of Lower California, and Puerto 

 Refugio, Angel de la Guarda Island, Gulf of California, Mexico, to 

 Santa Elena Bay, Ecuador. In addition to the above, 6 specimens from 

 a single Askoy station. (Garth, 1948) 



Measurements: Largest specimen, male: length 7.6 mm, width 11.8 

 mm, rostrum 1.2 mm, width 1.2 mm, cheliped 10.6 mm, merus 4.6 mm, 

 manus 6.4 mm, dactyl 3.0 mm, height of palm 2.8 mm. Female specimen: 

 length 5.9 mm, width 9.0 mm. 



Color in life: Carapace pinkish buff, rostrum orange red. Dorsal high 

 ridge and broad margin of carapace alizarine pink. Eyes dark brown. 

 Chelipeds creamish buff with touches of pink on teeth and ridges. Ambu- 

 latory legs semitransparent with light touches of pink. Ventral side light 

 buff with a few small spots of rose red. (Petersen, of a specimen from 

 Puerto Refugio, Angel de la Guarda Island, Mexico) 



Entire dorsal surface cinnamon buff, slightly darker on frontal areas. 

 Eyes brown. Ambulatory legs very light. (Petersen, of a specimen from 

 Parker Bay, Costa Rica) 



Habitat: Of the 21 dredge stations, 8 were sand bottom, with shell 

 present in 4 and nullipore in 1 ; 5 were mud bottom, with sand in 4 and 

 shell in 1 ; 3 were rock bottom, with mud and sand, shell, and gorgonians 

 in 1 each ; 3 were in shell bottom, with sand in 1 ; and 1 each were 

 coralline and nullipore alone. 



Depth: 2-32 fathoms. Once to 48 fathoms. 



Size and sex: Males are from 2.85 to 7.6 mm, females from 3.7 to 

 5.9 mm, the single ovigerous female 3.9 mm. Pleopods may be distin- 

 guished in the smallest males. 



Breeding: March at Bahia Honda, Panama. 



Remarks: The shallow bays and gulfs of Costa Rica and northern 

 Panama appear to provide optimum living conditions for this diminutive 



