78 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



There is a small wedge-shaped rostrum, either wholly chitinous or 

 with a very small calcareous center; often it is hardly noticeable, and 

 sometimes apparently wanting. 



The rostral latus is extremely narrow and long. The inframedian 

 latus is long and narrow, the carinal and rostral sides parallel, upper 

 end truncate, and the lower end somewhat dilated, basal margin 

 straight. The umbo is at the middle close to the basal margin. 



The carinal latus is irregularly triangular, the carinal margin long- 

 est, straight. The basal margin is oblique, straight, curving into the 

 concave or straight upper margin. The umbo is basal and those of 

 both latera are contiguous below the carina, but not projecting. 



The peduncle is short, with ten rows of about ten transversely 

 lengthened scales, of which only the ridges are calcitied. 



Length of capitulum 20, breadth 1-1 mm.; length of peduncle 8 nun. 

 Length of carina 19, diameter at base 5 mm. 



A series of 10 individuals was taken at the t^^pe-locality. The cal- 

 cified portions of the plates are comparatively larger in the 3"oung 

 specimens with a capitulum 13 mm. long, but otherwise similar to the 

 adult stage. In some examples a small triangular rostrum is distinctly 

 developed, sometimes with a minute calcified center; but in others it 

 can not be distinguished. The largest capitulum is 21 mm. long. 



A single mutilated capitulum was taken at Station 2980. 



In the figured adult the umbo of the carina is worn, as is usual in 

 large specimens of the species. An immature individual of the tvpe 

 lot, with the capitulum narrower and the carina perfect, is also illus- 

 trated. It measures, length of capitulum 17, width 10 mm. The 

 carina is less arched in young than in old examples. 



This species is closely related to S. invperfectum, of the east coast of 

 the United States, but it difi'ers by the narrower rostral latera, the less 

 projecting umbones of carina and carinal latera, the less distinctly 

 wineglass shaped inframedian lateral plate, the longer tergo-lateral 

 lobe of the scutum, etc. 



8. sanctseharharae, and S. imperfectum are related to xS'. gruveli 

 Annandale, from the Indian Ocean, yet among other difi'erences they 

 are unlike S. gruveli in having the umbo of the carina much farther 

 removed from the apex of the plate, the upper latus is more broadly 

 triangular, and the scales of the peduncle are smaller. (Fig. 31.) 



SCALPELLUM LARVALE Pilsbry. 



1907. S. larrule Filsbry, Bulletin of the Bureau of Fisheries, XXVI, p. 194, 

 pi. VI, figs. 2-6. 



r?//;«.-Cat. No. 32417, U.S.N.M. 



Type-locality. — Alhatross Station 4353, off Point Loma Light- House, 

 California, fi39 fathoms. 



