been pointed out by Rathbun (1925), and Garth 

 (1958) for related forms. Young individuals are 

 much different in shape from adults, having a 

 width considerably less than length (width about 

 70 percent of length including spines and ros- 

 trum), whereas the mature animals are more 

 rounded in contour (large adult male, with about 

 90 percent of length). Old individuals have a 

 thicker coating of hair than immature ones, espe- 

 cially on the chelipeds. Chelipeds in old indi- 

 viduals become quite large and stout with the 

 palm compressed (length more than twice that 

 of carapace). The young have fewer spines than 

 adults, the hepatic region is not expanded and 

 bears only one marginal spine as opposed to three 

 spines in adults. 



Habitat. — The species has been found on a va- 

 riety of bottoms, from gray mud, through various 

 grades of sand, to sand-shell, coral, and rock 

 (Rathbun, 1925). Twenty to 124 fathoms. 



Type locality. — Off Cape Lookout, N.C., 124 

 fathoms. 



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

 Florida Straits and Gulf of Mexico off Mobile 

 Bay, Ala. 



Remarks. — Ovigerous females have been re- 

 ported from South Carolina in December (Rath- 

 bun, 1925). 



Genus Macrocoeloma Miers, 1879 



Garth, 1958, p. 4,12. 



KEY TO SPECIES IN THE CAROLINAS 



a. Carapace without dorsal spines in addition to epi- 

 branchial and posterior spines trispinosum (p. 263). 



aa. Carapace with dorsal spines in addition to epibran- 

 chial and posterior spines camptocerum (p. 264). 



Macrocoeloma trispinosum (Latreille) . Grass crab, sponge 

 crab, decorator crab 



Figures 243, 245J 



Pisa trispinosa Latreille, 1825, p. 142> 



Macrocoeloma trispinosum: Hay and Shore, 1918, p. 457, pi. 38, 

 fig. 11— Rathbun, 1925, p. 466, text-fig. 132, pi. 166, fig. 1; pi. 

 167 (rev.). 



Recognition characters. — Carapace irregularly 

 triangular, body and legs with velvety covering 

 of short brown hairs, thick and swollen, wide at 

 level of orbits, narrowing distinctly in hepatic 

 portion, widening again posteriorly. Middorsal 

 region much elevated and bearing four low, 

 rounded tubercles or bosses, one on gastric, one on 

 cardiac, and one on each epibranchial region. 



Figure 243. — Maei-ocoeloma trispinosum (Latreille). A, 

 small male in dorsal view, legs of left side not shown, 

 10 mm. indicated ; B, right chela of adult male in 

 frontal view. 



Posterolateral angle prolonged into a long flat- 

 tened spine directed obliquely outward and back- 

 ward, sometimes curved upward; posterior mar- 

 gin with broad, median, triangular projection 

 with tip sometimes slightly recurved. Rostrum 

 formed of two somewhat flattened horns adjacent 

 and subparallel at base, divergent distally. Eyes 

 retractile within roomy, projecting, tubular orbits, 

 upper margin of orbit deeply emarginate, pre- and 

 post-ocular teeth prominent, preocular teeth 

 curved forward. Basal article of antenna with 

 inner angle produced, exceeding frontal margin, 

 and forming a broad spine directed obliquely out- 

 ward at each side of rostrum. 



Chelipeds of male narrow, approximately as 

 long as carapace; merus nodose; palm with sub- 

 parallel sides; dactyl approximately half as long 

 as upper margin of palm and lightly furrowed 

 above. Walking legs rather slender, slightly 

 nodose. 



Abdomen with seven separate segments in both 

 sexes. 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



263 



