88 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



lateral marg-in is straight and nearly parallel to the occludent. The 

 straight basal margin meets the others in right angles. 



The tergum is triangular, somewhat longer than the scuta. The 

 occludent and basal margins are slightly convex; the carinal margin 

 is slightly concave near the summit, a little convex- elsewhere. 



The carina is evenly curved with apical lunbo. The roof is Hat 

 between strong- bordering ribs. The sides are wide and divided b}^ a 

 curved sulcus. There are rather deep, spaced growth lines. The 

 basal marg-in is convex. 



The upper latus is c|uadrangular, the scutal and carinal margins par- 

 allel, the carinal about half as long as the scutal. The tergal and basal 

 margins are straight, longer than the carinal. The umbo is apical. 



The rostrum is quite small and triangular. The rostral latus is 

 trapezoidal, with parallel upper and basal margins, the l)asal much 

 the shorter. The height of the plate is scarcely half its length. 



The inframedian latus is narrowl}' ti'iangular, the base about half 

 the height. Umbo apical. There is an inconspicuous triangular wing 

 at the carinal side of the apex. 



The carinal latus is very irregularly pentagonal, as wide as high. 

 The carinal margin is concave. The umbones project a little l)e\'ond 

 the carina and are somewhat recurved; the margin below them is 

 convex. The portions of the carinal latera, seen in a dorsal view, are 

 ol)liqnel3" triangular, the roof of the carina extending triangularly 

 between them to the peduncle. 



The peduncle is ver}^ short, closely covered with transverseh^ 

 lengthened scales, in about 18 rows of ab(5iit 7 or 8 scales each. 



Length of the capitulum 10, breadth 5.4 nnn. Length of the 

 peduncle 2 mm. Length of the carina 9.5, diameter at l)ase 2 mm. 



This is a strong, robust little species, with unusually emphatic 

 concentric sculpture of striie and spaced grooves on the plates. It is 

 most nearly related to S. atlantieum Gruvel," l)ut in *s'. lorKjicarlna- 

 tuin the carina is less curved above, its sides are wider near the base, 

 and the ribs bordering the roof are ver}' strong. The rostrum and 

 inframedian latus are also unlike in the two forms. <S'. ]on(/>carin((tum 

 ditl'ers from S. portorican\(ii> by the erect shape of the inframedian 

 latus, the wider sides and heavy bordering ribs of the carina, and l)y 

 the general shape of the capitulum, which tapers toward the l)ase^ 

 and is more lengthened. It is probably related also to the still 

 untigured S. mauimillattnn Aurivillius, from off the Azores, but the 

 rostral latera are of a different shape. S. tenue Hoek is also related, 

 yet several of the plates differ in shape, and ^S*. Jongicarlnation. has a 

 distinct rostrum. The Californian xS'. gniveUanuvi Pilsbry is allied, 

 but has a shorter carina. In xS'. loiigicaririatuin the carina is neai'ly as 



"Expedition dii Travailleur et du Talisman, Cirrhipedes, pi. ii, figs. 17, 18. 



