14 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



and with the umbo at or below the middle, never apical. Besides the 

 species mentioned below, the following seem to belong to this group: 

 S. ealcaratum Aurivillius, S. ornatum Gray, S. salartiae, Gruvel, S. 

 hamatum Sars. 



KEY TO NORTH AMERICAN SPECIES. 



a. Umbo of the scutum at its upper third; carina angular near the middle; umbo of 



the inframedian latus subcentral. Gulf of Mexico S. gibbum. 



aa. Umbo of the scutum near the apex; carina regularly bowed with apical umbo; 

 inframedian latus large, pentagonal, or rounded, with subcentral umbo; pro- 

 fusely hairy. Californian forms. 



b. Valves imperfectly calcified at the indistinct edges, the chitinous sutures 



very wide S. californicum. 



bh. Valves strongly calcified, with distinct edges; sutures narrower. 



<S'. osseum. 

 aaa. Umbo of the scutum apical, that of the quadrate inframedian latus on its rostral 

 border. North Atlantic and Arctic forms. 



h. Width of the inframedian latus less than half its height; rostrum nar- 

 row, tapering upward <S'. pressum. 



bb. "Width of the inframedian latus more than half its height. 



c. Umbo of the inframedian latus jiear the middle of its rostral edge. 



d. Rostrum narrow S. stroeinn. 



dd. Rostrum wide, triangular *S'. stroemii latirostrum. 



cc. Umbo of the inframedian latus near the rostro-basal angle of the 

 plate S. stroemii substroemii. 



This section comprises several subsidiary phyla, and the group of 

 S. stroemii could with some reason be removed to form a separate 

 section, characterized by the high rostral latera of the female and 

 hermaphrodite forms and the more degenerate complemental males, 

 which have been investigated in S. stroemii and S. nymphocola by 

 Hoek. 



In S. patagonicum and S,. inerme there has been reduction of the 

 calcareous portions of the valves, the general structure not being 

 much altered otherwise. 



GROUP OF SCALPELLUM SCALPELLUM. 



SCALPELLUM STEARNSII Pilsbry. 



1890. Scalpellum steamsii Pilsbry, The Nautilus, IV, p. 96 (December, 1890); 

 Proc. Acad. Nat. Sci. Phila., 1890, p. 441 (Feb. 3, 1891).— Gruvel, Mono- 

 graphie des Cirrhipedes, 1905, p. 44. 



Localities.— Cat. No. 32873, U.S.N.M., east coast of Japan between 

 the bay of Tokyo and the Inland Sea, F. Stearns, one of the original 

 lot, dry. No. 32874, Japan, collector unknown, dry. No. 22152, 

 Japan, H. Loomis, dry. No. 32875, Albatross Station 3704, Seno Umi, 

 off Hondo Island, Japan, 94 fathoms. 



Two of the four specimens in the collection surpass the type of the 

 species in size, measuring as follows: 



