Known range. — Potomac River, Gunston, Va., 

 to Rio de Janeiro, Brazil. 



Remarks. — This large species is one of the com- 

 monest conspicuous hermit crabs of the shore 

 region of the Carolina bays. It has a broad range 

 along the western Atlantic, and Holthuis (1959) 

 has given new distribution records, as well as a 

 history of its early recognition in this hemisphere. 



Ovigerous females have been reported from 

 Surinam in July and August (Holthuis, 1959) 

 and from Florida in October (Provenzano, 1959). 



Genus Petrochirus Stimpson, 1858 



Stlmpson, 1858, p. 233 (71). 



Petrochirus diogenes (Linnaeus) 

 Figure 98 



Cancer Diogenes Linnaeus. 1758. p. 631. 



Petrochirus bahamensis: Hay and Shore, 1918, p. 410, pi. 30, 

 fig. 6.— Schmitt, 1935a, p. 206, fig. 66.— Provenzano, 1959, p. 378, 

 fig. 8.— 1961, p. 153 (rev.). 



Petrochirus diogenes: .Holthuis, 1959, p. 151 (rev.). 



Recognition characters. — Anterior shield of 

 carapace flattened, as broad as long, rough, un- 

 even, and with scattered tufts of hairs ; front tri- 

 lobate, rostrum about as long as lateral projec- 

 tions. Eyestalks straight, dilated distally, with a 

 tuft of hair above corneal surfaces and scanty 

 tufts near base; eye scales broad basally, acute 

 anteriorly with indistinct serrations. Antennular 

 peduncles reaching or exceeding eyestalks. Anten- 

 nal peduncles shorter than eyestalks; acicles 

 slender, hairy, and minutely spined. 



Chelipeds massive, subequal, right slightly 

 larger; hands and carpi coarsely roughened with 

 grouped tubercles separated by appressed setae on 

 upper and, to some extent, lower surfaces, becom- 

 ing spinose along inner margin; fingers opening 

 obliquely, major chela with fingers tuberculate on 

 crushing edges, minor chela with fingers some- 

 what spooned, cutting edges sharp, tips corneous. 

 First two pairs of walking legs with carpus 

 ornamented above like chelae; propodi similar 

 with clusters of hairs beneath; dactyls with 

 slightly twisted rows of spines and dense setae; 

 propodi and carpi, especially of first walking legs, 

 with dorsal row of dark-tipped spines. Third 

 legs subchelate; last legs chelate and turned up 

 against side. 



Measurements. — Length of carapace: male, 75 

 mm.; female, 44 mm. 



Figube 98. — Petrochirus diogenes (Linnaeus). Female in 

 dorsal view showing well-developed triramous pleopods, 

 X 0.35 (after Provenzano, 1959). 



Color. — Generally reddish; chelipeds reddish 

 except between fingers, and white spots on carpal 

 articles; antennal and antennular peduncles 

 longitudinally striped with red and white, 

 antennal flagella transversely banded with red 

 and white (Provenzano, 1959). 



Habitat. — Mud, mud and shell, and sand 

 bottoms. Common on shrimping grounds near 

 Tortugas, Fla. (Provenzano, 1959), in the western 

 Gulf of Mexico (Hildebrand, 1954, 1955), and on 

 fishing grounds southeast of Cape Lookout, N.C., 

 in about 18 fathoms; to 50 fathoms (Provenzano, 

 1959; Holthuis, 1959). 



Type locality. — Near shores of Bahama Islands 

 (Catesby, in Holthuis, 1959). 



Known range. — Off Cape Lookout, N.C., to 

 Brazil; West Indies. 



Remarks. — The genus Petrochirus has a fossil 

 record extending from the Cretaceous to the pres- 



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