290 BULLETIN 03, UNITED STATES NATIONAL MUSEUM. 



sharp, and arched. The outer layer is chamois colored, and scaly. 

 There is a groove down the middle of each compartment, and a tri- 

 angular smooth area, where the outer layer is wanting, at the base. 

 A slight ridge encircles the wall above the middle, marking the 

 limit of the portion of the barnacle embedded. The scaly surface 

 is produced by delicate ribs bearing series of flat lobes or digitations, 

 the ribs being arranged en chevron on each compartment, and the 

 lobes or scales of one rib imbricating upward over the bases of the 

 next. Upon the upper-part, above the encircling ridge, the scales are 

 larger and arranged in nearly horizontal rows. 



The sheath covers fully two-thirds the height of the compart- 

 ments, is glossy, white, and regularly grooved transversely. Its 

 lower edge is continuous with the smooth inner surface. The basal 

 edges of the wall plates are thin and smooth. 



The basis is entirely membranous and flat. 



Rostrocarinal diameter, G.7 mm.; lateral diameter, 6 mm.; height' 

 3 mm. 



The opercular valves protect less than half the area of the orifice, 

 but extend nearly its whole length. They are very thin, glossy, 

 white, and smooth both outside and within. They are long and nar- 

 row, the terga in contact with the scuta but not articulated or inter- 

 locking in any way. The scuta are longer than the terga, tapering 

 to a point at the rostral end, obliquely rounded at the tergal end. 



Costa's paper of 1838, describing and figuring Coronula elcgans, 

 was not contained in our library at the time I described Stomato- 

 lepas, and his species has never been mentioned by any other author 

 so far as I know. While it seems likely that the Mediterranean and 

 American forms are specifically the same, there are certain differ- 

 ences which influenced me to leave them apart until an actual com- 

 parison of Mediterranean examples can be made with our form. 

 Costa describes elegans as orange in color, but this might be on 

 account of the dry tissues of the host adhering to the barnacle. His 

 figure shows the parietes evenly scaled, while in our form the squama - 

 tion of the upper part differs rather conspicuously from the lower 

 portion. This would be an important distinction if confirmed, but 

 it might easily be due to insufficient observation on the part of Costa's 

 artist. 



Family CHTHAMALIDvE. 



1854. ChthamalincB DABWIN, Monograph, p. 446. 



Sessile barnacles in which the walls are not porous ; the rostrum 

 has alee; or when concrescent with the rostrolateral compartments, 

 the composite plate has radii, or overlaps the lateral compartments. 

 The rostrolateral compartments (when not fused with the rostrum) 

 are without alse on either side. The labrum has a concave, not notched 

 edge, and is often swollen or " bullate " externally. The lower angle 



