Measurements. — Carapace: male, length, 34 

 mm. ; width, 29 mm. 



Variations. — Eathbun (1925) discussed varia- 

 tion in this species throughout its known range. 

 Body shapes falling into three general series are 

 distinguishable. In the first, the typical form, the 

 posterolateral prominences are narrow, with reg- 

 ularly tapering spines, projecting beyond the gen- 

 eral outline of the carapace and directed more or 

 less backward, and sometimes strongly curved 

 from base to tip with the concavity forward. Tiie 

 carapace is considerably constricted behind the 

 orbits. The orbits are prominent owing to this 

 constriction, and the pre- and post-ocular teeth 

 are strong, the former directed forward and 

 curved. The upper edge of the orbit is deeply 

 emarginate. The four large tubercles or bosses are 

 prominent, some or all with an acute tip, that on 

 the gastric region sometimes nearly a spine. 



In the second series, treated by Rathbun as an 

 unnamed variety, the posterolateral prominences 

 are wider than in the first series, less spinelike 

 and more laminate, their hind margins nearly 

 transverse. The carapace is less narrowed behind 

 the orbits, the orbital teeth less marked, though 

 the preocular tooth is directed forward and a 

 little curved, and the superior emargination less 

 deep. The four large dorsal bosses are lower than 

 in series one, but the gastric boss tends to be 

 surmounted by a sharp tubercle or granule. 



In series three, called M. t. nodipes, the postero- 

 lateral prominences are broader and more obtuse 

 than in series two with their margins almost con- 

 tinuing the margin of the carapace. The carapace 

 is constricted little or not at all behind the orbits ; 

 the preocular tooth is acute but not prominent, 

 and the postocular tooth blunt or subacute with 

 both teeth somewhat more prominent in young 

 individuals than in old ones. The orbit has a 

 slight emargination in the upper border. The 

 dorsal bosses are lower than in the other series, 

 smoothly rounded and blunt. 



In the three series the posterior median spine 

 varies in a manner similar to the lateral spines. 

 Within the three series, the rostrum shows great 

 variability in length, direction, and curvature of 

 the horns. 



< 'olor. — Hairs yellowish or reddish brown 

 (various authors). 



Habitat. — In North Carolina, this species has 

 been found in seaweed in Beaufort Harbor, in the 

 ocean on floating masses of Sarga-ssum, and 

 dredged from offshore reefs. Elsewhere it has 

 been found in a variety of situations, from pilings 

 and mangrove roots to weedy rocks, coarse-coral 

 sand, sand-shell, and broken-shell bottoms. The 

 species is often concealed by a covering of sponge. 

 Shallow water to 45 fathoms. 



Type locality. — Nouvelle Holland (?) [error]. 



Known range. — Beaufort, N.C., to Alligator 

 Harbor, Fla. ; Yucatan; through West Indies to 

 off Cape Sao Roque, Brazil. 



Remarks. — Ovigerous females have been re- 

 ported from southern Florida in December, Cuba 

 in April, and Jamaica and St. Thomas in July 

 (Rathbun, 1925; U.S. National Museum records). 



Macrocoeloma camptocerum (Stimpson) 

 Figures 244, 245K 



Pericera camptocera Stimpson, 1871a, p. 112. 

 Macrocoeloma campterocerum: Hay and Shore, 1918, p. 457, pi. 

 Rathbun, 1925, p. 469, pi. 174, fig. 4 ; pi. 270, fig. 2 



38, fig. 12 

 (rev.) 



Recognition characters. — Carapace irregularly 

 triangular; surface covered with short, close 



Figure 244. — Macrocncloma ramptnrcrum (Stimpson). 

 Male in dorsal view, legs of left side not shown, 10 mm. 

 indicated. 



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