52 



BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



wide. The bii.sal inarg-in is convex. The lines of growth on tlie roof 

 curve deeply downward. 



The upper hitus is irregularly pentagonal. The scutal niarg:in is 

 much the longest and straight; the tergal shorter and straight, '^he 

 carinal margin and that against the carinal latus are still shorter, sub- 

 equal. The l)asal margin, against the inf ramedian lat(^ral pkte", is very 

 short. The apex is subterminal. 



The rostrum is reduced to a linear rudiment, separating the rostral 

 latera along the upper half of their contiguous borders. 



The rostral latus is subtriang-ular, the three sides about equal. The 

 scutal margin is slightly concave, the ventral margin straight, and the 

 baso-lateral margin is convex. 



The inframedian latus is oblong, narrow, contracted slightly below 



the middle, a little dilated above and below the contraction, the basal 



segment much smaller than the upper. The umbo is close to the base. 



The carinal latus is very long and narrow, nearly as long as the 



scuta. The carinal 

 margin is straight, the 

 lateral and basal mar- 

 gins convex. The um- 

 bo is close to, but not 

 at, the base of the 

 plate, l)elow the cari- 

 na. It does not pro- 

 ject beyond it. The 

 two plates meet in a 

 ver}' short straight su- 

 ture below the carina. 

 The peduncle is very 

 short, closelv covered 

 with large transversely lengthened scales, in six rows of about 5 scales 

 each. 



Length of the capitulum 8, breadth 3.8, mm.; length of the 

 peduncle 1.8 mm.; length of the carina (5.3, diameter at base 1 mm. 

 The more conspicuous features of this small species are its exces- 

 sively narrow rostrum, the rounded roof of the carina, the somewhat 

 hour-glass shaped inframedian latera, and the very long and narrow 

 carinal latera. Where the rostrum is so reduced as in this .species, its 

 complete elimination in some individuals would occasion little surprise. 

 Only two specimens were taken, the second one being immature, 

 about half the size of tlie type. They were seated upon a slender 

 annelid tube. 



S. gracilis is closely related to S. 7iov3e,zelandis6 Hoek and S. 

 iiavum Hoek, both antipodal species. 8. luwsezelandiae. differs by hav- 

 ing the carina flat-roofed. 6'. -flavum. is very close to 8. gracilius^ but 



Fig. 17.— Scalpellum gracilius. a, lateral view x 5, with 



DETAILS OF, b, ROSTRUM AND, C, CARINA. 



