THE SPIDER CRABS OF AMERICA 561 



Variation. — Rostrum usually more acute in young than in adult; 

 in the youns; there is also oonsiderahle pubescence along angles of 

 chelipeds and especially in branchial and frontal regions, sometimes 

 covering greater part of carapace, while carapace of adult is commonly 

 smooth. Middle of posterior margin of carapace more prominently 

 rounded in female than in male. 



Range. — From the Farallones, California, to Los Coronados Islands, 

 Mexico. Boca de Los Piedras, Sinaloa, Mexico (Lockington) . Depth, 

 13 to 50 fathoms. 



Material examined. — See table, page 562. 



Family HYMENOSOMIDAE 



Pinnotheriens Milne Edwards (part), Hist. Nat. Crust., vol. 2, 1837, p. 28. 

 Pinnotheridae-Hymenicinae Dana, U. S. Expl. Exped., vol. 13, Crust., 



1852, pp. 379 and 384. 

 Hymenosminae [Hymenosominae] Milne Edwards, Ann. Sci. Nat., Zool., 



ser. 3, vol. 20, 1853, p. 221 [187]. 

 Hymenosomidae Stimpson, Proc. Acad. Nat. Sci. Philadelphia, vol. 10, 



1858, p. 108 [54].— Borradaile, Ann. Mag. Nat. Hist., ser. 7, vol. 19, 



1907, p. 480.— Alcock, Journ. Asiat. Soc. Bengal, vol. 69, 1900, pp. 280, 



282, 285, 291 and 385. 

 Pinnotheridae-Hymenosominae Miers, Challenger Rept., Zool., vol. 17, 1886, 



pp. 274-275. 

 Majoidea-Hymenosomidae Ortmann, in Bronn's Thier Reich, vol. 5, pt. 2, 



Arthropoda, 1898, p. 1168. 

 Hymenosomatidae Stebbing, Marine Invest. S. Africa, vol. 4, 1905, p. 49. 



Carapace thin and flat. Chelipeds not long or especially mobile 

 or with fingers bent at an angle with the hand. Male openings 

 sternal. There are no orbits and the eyes are exposed and little 

 retractile. The palp of the external maxillipeds articulates near the 

 antero-external angle of the merus. Antennular fossae shallow and 

 ill defined. Antennal peduncle slender. No hooked hairs. 



Genus HALICARCINUS White 



Halicarcimis White, Ann. Mag. Nat. Hist., vol. 18, 1846, p. 178; type, H. 



planatus (Fabricius). 

 Liriopea Nicolet, in Gay, Hist. Chile, Zool., vol. 3, 1849, p. 158; type, L. 



leachii (Gu^rin). 



Epistome well defined. Antennules not concealed by front. No 

 septum between antennules. Merus and ischium of outer maxilli- 

 peds of subequal size. 



South Temperate zone. Only one species is American. 



