THE BARNACLES IN THE U. S. NATIONAL MUSEUM. 



57 



the carina reaches onh' to ahout the lower fourth of the carinal mar- 

 gins of the terg-a. The ahnost concrescent infraniediaii and carinal 

 latera are a peculiar feature of the new form. At tirst sight infra- 

 median latera seem to be wanting. (Fig. 20.) 



SCALPELLUM MICRUM, new species. 



Type.—C2it No. 32879, U.S.N.M. 



Ti/2)e-locaJ!fy. — A/hatro.ss Station 2H08, between the Bahamas and 

 Cape Fear, North Carolina, in 294 fathoms, on a dc1icat(> Tlydroid, 

 bottom temperature 4(5. 3' F. 



The capitulum is oval, widest in the middle, tapering toward both 

 ends; the ventral and dorsal margins are about equally curved; com- 

 pressed and white; composed of fourteen fully calcified plates, sepa- 

 rated by linear sutures. There is no perceptible cuticle. The plates 

 are faintly marked with lines of growth 

 and a few very faint radial stria. 



The scutum is about twice as long as 

 wide, the occludent and lateral margins 

 parallel, the basal margin nearly at right 

 angles to them. The upper third of the 

 occludent margin bends backward. The 

 umbo is acute, terminal, and recurved. 



The tergum is wider and longer than 

 the scutum, triangular. The occludent 

 margin is convex; scuto-lateral margin 

 convex. The carinal margin is sinuous, 

 the upper part being concave, the lower 

 somewhat convex. 



The carina is short, simpl}^ arched, with 

 an apical mucro. The roof is rounded, FrG.21.-scALPELi.rM micrum xs, with 



,, 1 • ; ,1 .1 . DETAIL VIEW OF ROSTRUM. /,. 



passing directly into the narrow sides; it 



is transversely marked with deepU^ arcuate growth-lines. The apex 

 reaches to the upper third of the length of the carinal margin of the 

 tergum. The base is rounded. 



The upper latus is trapezoidal with straight margins, the carinal 

 margin nearly half as long as the scutal, the tergal and basal margins 

 about equal. The apex is terminal at the scuto-tergal angle. 



The well-developed rostrum forms a band about one-fifth as wide as 

 long, and slightly narrower above than at the base. It extends the 

 whole length of the adjacent latera. 



The rostral latus is triangular, with the basal angle of the triangle 

 truncated. The three sides are about equal, the two upper angles 

 also equal. 



The inframedian latus is narrow, triangular, its height equal to that of 

 the rostral latus, and about double the basal width. The umbo is apical. 



