12 BiTLLprriN 00, unitkd >^tates national museum. 



plate. The basal margin is coiu'caled undor the lower whorl of 

 plates. 



The tcrg-um is in part concealed under the margins of the scuta and 

 carina. The visible part is divided into two equal areas by a prominent 

 median ridge running from apex to base. The summit is erect, only 

 a triHe recurved. 



The carina is not much curved, its apex not inserted between the 

 terga. The roof i.s strongly carinate along the median line, sloping 

 and sculptured with radial strite on each side of the keel. It is very 

 wide at the base. The sides are narrow and incurved. 



The rostrum is triangular, nearh^ as wide as high, with incurved 

 apex, and having a very strong median longitudinal rib. 



The rostral lateral plate is obliqueU' triangular, with incurved apex. 

 The surface is coarsely sculptured with st^eral ver}' low radial ribs, 

 numerous fine radial striai, and curved, coai'se, low growth-wrinkles. 

 The base of the plate overlies the adjacent bases of the rostrum and 

 inframedian latera. There is no subrostrum. 



The median lateral plate is oblique, triangular, much wider than 

 high, with the apex incurved and twisted. A strong flat-topped rib 

 runs from the apex to the basal margin, which in the middle rests 

 directly upon the peduncle. 



The carinal latus is oblique, triangular, with the apex curved under 

 those of the inframedian plates. The surface is ribbed. 



The subcarina is triangular, usually a83^mmetrical, with an incurved 

 apex. 



The peduncle is very short, and densely covered with large, strongly 

 imbricating white scales. 



Length of the capitulum 40, width 34 mm. Length of the visible 

 part of the carina 38, diameter l-i mm. (Fig. 3.) 



The plates show some variations in shape in the four specimens 

 taken, the sul)carina especially being irregular. It is bent more or 

 less to the right of the median line in two specimens from Station 

 2660, and to the left in two from Station 2415. In one of those from 

 the latter station the carina and scuta are straightened, the apices pro- 

 jecting, exactl}^ as in S. trispinosuia Iloek. 



Two specimens from Station 2415 measure: Length of capitulum 35, 

 width 28 mm. Length of peduncle 12 mm. 



Length of capitulum 28, width 22 nuu. Length of peduncle 15 mm. 



8. superbum is closely related to S. genima Aurivillius,^' but it 

 differs by the much longer scuta, which reach almost to the summits 

 of the terga, by the far narrower terga, less recurved at the apices; 

 b}^ the much wider roof of the carina, and finally by the compara- 

 tivel}' smaller size of the plates of the lower whorl, and the different 



"Stndien iiber Cirripeden, in Koii":!. Hveiipka Voteii.«kaps-Aka<l. Handlinszar, 

 XXVI, 1894, no. 7, p. 41. East coast of Givcnland, in 1.800 meters. 



