THE SPIDER CRABS OF AMERICA 563 



HALICARCINUS PLANATUS (Fabricius) 



Plate 202, fig. 5; plate 283 



fCancer orbiculus Fabricius, Syst. Ent., 1775, p. 402 (type-locality, New 

 Zealand; type in Brit. Mus.). 



Cancer planatus Fabricius, Syst. Ent., 1775, p. 403 (type-locality. Terra del 

 Fuego; type in Brit. Mus.). 



Leucosia planata Fabricius, Entom. Syst., Suppl., 1798, p. 350. 



Halicarcinus planatus White, Ann. Mag. Nat. Hist., ser. 1, vol. 18, 1846, 

 p. 178, pi. 2, fig. 1.— Dana, U. S. Expl. Exped., vol. 13, Crust., pt. 1, 

 1852, p. 385; atlas, 1855, pi. 24, figs. 7a and 6.— Stebbing, Proc. Zool. 

 Soc. London, 1900, p. 524, pi. 36B, and synonymy, except probably 

 Hymenosoma planatum Haswell; Trans. Roy. Soc. Edinburgh, vol. 50, 

 1914, p. 271, and synonymy. — Chiltov, Subantarctic Ids. of New Zea- 

 land, art. 26, 1909, p. 609. — Doflein and Balss, Jahrb. Hamburg. Wiss. 

 Anst., vol. 29, 1912, p. 35. 



Liriopea leachii Nicolet, in Gay, Hist. Chile, Zool., vol. 3, 1849, p. 160; 

 atlas, vol. 2, 1854, Crust., pi. 1, figs. 1-1/; type-locality, Chile; type not 

 extant). 



Liriopea lucasii Nicolet, in Gay, Hist. Chile, Zool., vol. 3, 1849, p. 161 

 (type-locality, Chile; type not extant). 



f Halicarcinus pubescens Dana, Proc. Acad. Nat. Sci. Philadelphia, vol. 5, 

 1851, p. 253; U. S. Expl. Exped., vol. 13, Crust., pt. 1, 1852, p. 386; 

 atlas, 1855, pi. 24, fig. 8 (type-locality, off Cape Blanco, Patagonia, 50 

 fathoms; type not extant). 



Diagnosis. — Lateral teeth of carapace below the marginal rim. 

 Median frontal tooth a little smaller and less advanced than the 

 lateral teeth. Supero-terminal tooth of menis of cheliped absent or 

 obscure. Dactyli of ambulatory legs moderately curved. 



Desci'iption. — Carapace distinctly broader than long, ovate, nar- 

 rowed before; flat or even depressed, surrounded except the marginal 

 teeth by a sharp rim; median grooves linear, the branchial groove 

 strongly angled, the gastro-cardiac groove bent slightly backward at 

 the middle; a median cardiac groove. Three similar frontal teeth, 

 the median somewhat smaller. Two lateral teeth forming angles 

 below the marginal rim; the posterior of these teeth is well devel- 

 oped and acute; the anterior is smaller and variable, usually obtuse, 

 sometimes acute, sometimes obsolescent on one or both sides. 



Chelipeds stout, especially in male; palms swollen, fingers nearly 

 horizontal, gaping slightly in basal half, prehensile margins denticu- 

 late, a tooth on the dactyl within the gape. Legs slender, diminishing 

 in length from the first to the fourth pair, the longer pairs exceeding 

 the chelipeds; dactyli flattened, not very slender, moderately curved. 



Abdomen of male constricted between the sixth and seventh seg- 

 ments, the seventh segment subtriangular. 



Color. — Varying from slaty-blue to reddish-broNMi, legs banded 

 (Mawson Exped.). 



Measurements. — Male (18209), length of carapace 8.4, width 

 10.3 mm. 



