dd. Dactyls of walking legs ending in a simple 

 spine usually with small, movable accessory spin- 

 ules on lower margin ; carapace longer than 

 broad. 



e. Front strongly tridentate in dorsal view ; cara- 

 pace slightly longer than broad ; chelipeds not 

 grossly sculptured. 



f. Cervical groove terminating anterolateral^ 

 in shallow marginal indentation at edge of 



carapace Porcellana sayana (p. 110). 



ff. Cervical groove terminating anterolateral^ 

 in a distinct longitudinal cleft at edge of 



carapace Porcellana sigsbciana (p. 111). 



ee. Front strongly trilobate in frontal view ; 

 carapace usually broader than long ; chelipeds 

 thick and grossly sculptured 



Megalobrachium soriatum (p. 112). 



Genus Petrolisthes Stimpson, 1858 



Sttmpson, 1858, p. 240.— Halg, 1960, p. 21. 



Petrolisthes galathinus (Bosc) 



Figure 83 



Porcellana galathina Bosc, 1801 (or 18021, p. 233, pi. 6, fig. 2. 

 Petrolisthes galathinus: Hay and Shore, 1918, p. 404, pi. 29, 

 fig. 1.— Haig, 1956, p. 22 (rev.).— 1960, p. 36. 



Figure 83. — Petrolisthes galathinus (Bosc). Animal in 

 dorsal view, fifth leg only of left side shown, 5 mm. 

 indicated. 



Recognition characters. — Carapace a little 

 longer than wide, covered with strong, transverse, 

 ciliated rugae, scarcely interrupted at grooves 

 separating well-marked regions; frontal region 

 granulate, metabranchial regions plicate. Front 

 produced into a broad, triangular, sinuous-sided 

 rostrum with a broad median groove usually 

 covered with short pubescence. Supraorbital 

 spine present, not distinct in large specimens; 

 postorbital angle produced into a small spine- 

 tipped tooth; epibranchial spine strong. Eyes 

 well developed. Antenna with first movable article 

 bearing an anteromedian, spine-tipped, lamellar 

 lobe; second and third articles lightly rugose. 



Chelipeds large, covered with strong, ciliated 

 rugae continuing obliquely and almost unbroken 

 across carpus and hand, broken into series of 

 shorter rugae on fingers; merus with a strong 

 rugose lobe at inner distal angle; carpus about 

 twice as long as wide, anterior margin with four 

 to six strong serrate spines, a row of spines on 

 posterior margin ; hand broad, flattened, rugae on 

 outer margin spiniform in smaller specimens, 

 outer margin often fringed with plumose hairs; 

 dactyl sinuous, fingers closing closely, a thick tuft 

 of pubescence below. Walking legs rugose; an- 

 terior margin of meri with fringe of plumose 

 hairs; all articles covered with long, nonplumose 

 setae; anterior margin of first and second legs 

 with six to nine spines, third with five to seven; 

 merus of first and second with a posterodistal 

 spine. 



Sternum, sternal plastron, abdomen, ventral 

 surface of outer maxillipeds, chelipeds, and walk- 

 ing legs covered with strong striations. 



Measurements. — Length of carapace: males, 7 

 to 17 mm.; non-ovigerous females, 6 to 11 (15?) 

 nun. ; ovigerous females, 7 to 14 mm. (Haig, 1960 ; 

 Holthuis, 1959). 



Color. — Grayish brown without markings in 

 life; in alcohol, light brown with purple or dark- 

 red lines and dots on rugae (Hay and Shore, 

 1918). Spaces between rugae yellow; lower sur- 

 face, including abdomen, deep red (Faxon in 

 Haig, 1960). 



Habitat. — Under stones and associated with 

 sponges, corals, and anemones in littoral ; in some- 

 what deeper water, from sand and sand-shell bot- 

 tom (Haig, 1960) ; low- water mark to 27 fathoms. 



Type locality. — Unknown. 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



107 



