Pearse, Humm, and Wharton (1942) stated 

 that where waves roll at the low-tide mark A. 

 cribrarius may scurry across sand and burrow 

 backward. In doing this, the crab flirts sand for- 

 ward away from the body with the chelipeds, 

 waves legs two to four rapidly from the median 

 line laterally, and moves the fifth legs posteriorly 

 and dorsally, thus sinking vertically into the sand. 

 Often the crabs bury themselves completely. The 

 heavy coat of hairlike setae on each side of the 

 mouth parts keeps out sand, and with the cheli- 

 peds held close to the body a clear channel is left 

 for currents from the branchial chamber. Ability 

 to maintain strenuous activity in the breaker zone 

 near shore may be partially explained also by 

 the relatively large respiratory surface in this 

 species (Gray, 1957). 



Genus Cronius Stimpson, 1860 



Rathbun, 1930a, p. 138. 



Cronius ruber (Lamarck) 



Figure 154 

 Portunu* ruber Lamarck, 1818, p. 260. 

 Cronius ruber: Rathbun, 1930a, p. 139, pis. 62-63 (rev.). 



Recognition characters. — Carapace hexagonal, 

 smooth, pubescent ; a sinuous transverse ridge ex- 

 tending between lateral spines, and another 



Figure 154. — Cronius ruber (Lamarck). Animal in dor- 

 sal view, legs of left side not shown ; ( redrawn from 

 Monod, 1956). 



shorter, transverse, biarcuate ridge about halfway 

 between this ridge and front. Front proper with 

 four teeth, not including inner orbitals; sub- 

 median pair of teeth most advanced; second pair 

 more pointed, and directed slightly laterad, sepa- 

 rated from notched inner orbitals by a deep cut. 

 Orbit nearly circular. Basal article of antenna 

 with spine below insertion of movable portion. 

 Anterolateral teeth unequal, alternating large and 

 small; lateral spine not strikingly enlarged. 



Chelipeds heavy; merus with four to six spines 

 in front, and with small distal spine behind; car- 

 pus with granulate ridges, one large internal 

 spine, and three small spines on outer surface; 

 hand with granulate ridges on all surfaces, armed 

 with four spines on superior surface, two on in- 

 ner and two on outer border. 



Measurements. — Carapace: male, length, 50 

 mm. ; width, 75 mm. 



Color.- — "Violet red or deep purple red more or 

 less marbled with a lighter shade or white. Ex- 

 tremity of all spines black." (Rathbun, 1930a.) 



Habitat. — Siebenaler (1952) reported C. ruber 

 as a "trash" form on the Tortugas shrimping 

 grounds; below low tide mark to 40 fathoms. 



Type locality. — Brazil. 



Known range. — South Carolina to State of 

 Santa Catarina, Brazil ; Lower California, Mexi- 

 co, to Peru and Galapagos Islands; west Africa- 

 from Senegal to Angola. 



Remarks. — Rathbun (1930a) reported ovige- 

 rous females from May through September in 

 Curasao, in June from Cuba, and in July from 

 Jamaica. 



Family Cancridae 



Carapace broadly oval or hexagonal. Last pair 

 of legs not adapted for swimming. Antennules 

 folding lengthwise. Antennae with flagella more 

 or less hairy. 



Genus Cancer Linnaeus, 1758 



Rathbun, 1930a, p. 176.— Hemming, 1958b, p. 51. 



MacKay (1943) gave a review of the modern 

 world distribution of members of the genus Can- 

 cer, as well as the geologic record which dates 

 from the Eocene Period. The modern distribu- 

 tion of the genus is limited, apparently by tem- 

 perature, to the temperate zones except along the 

 northwestern coast of South America in the cold 

 Humboldt Current. 



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