42 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



The barnacle is cream-white, very high, compressed laterally, the 

 movable plates approaching a vertical position. The apices of the 

 carina and rostrum project. Plates of the wall are rather thin, and 

 have a very narrow inflexed edge, like a hem, at the base. 



The movable scutum has two beaded, contiguous, articular ribs, 

 the second reaching the baso-tergal angle; outside of this the plate 

 is flat with sculpture of regular, imbricating, transverse ribs. The 

 tergal area is sunken and densely, finely striate. Inside, the tergal 

 and occludent borders are raised, the middle of the plate sunken. 

 The suture between scutum and tergurn is straight except near the 

 apices, where the scutum projects. 



The movable tergum divides into two subequal areas by a diagonal 

 beaded rib accompanied by a narrow groove. The scutal area is 

 hollowed out in the upper part. It is sculptured with narrow, curved 

 riblets parallel to the scutal suture. The other area is flat, with 

 sculpture of about 25 flat, imbricating ribs, which denticulate the 

 occludent margin. The interior face is smooth and flat. 



The fixed scutum has three areas, a triangular, wide median area or 

 paries, an almost equally large rostral, and a very narrow, radiiform 

 tergal area. The median area has a sculpture of imbricating, shingle- 

 like ribs parallel to the base. The other areas have narrower, steeply 

 ascending ribs. There is no internal myophore. 



The fixed tergum is the highest plate. Its raised median area or 

 paries is narrow, the two side areas large, and subequal. All are 

 sculptured like the fixed scutum. 



The carina curves around the cariiial end of the wall. It has 

 regular imbricating sculpture parallel to the basal margin, except on 

 the rostral side, where there is a shallow radial sulcus bordered by 

 vertically costate bands. There is also a very narrow rib running 

 along the scutal border. 



The rostrum is higher than the carina, with two radial sulci and 

 three flat, costulate ribs. The cariiiorostral suture is zigzag by the 

 interlocking of two conic teeth in each plate. 



Greatest length of base 7.6 mm.; length between apices of carina 

 and rostrum 9.8 mm.; greatest diameter of base 5.5 mm. Height 

 from base to apex of fixed tergum 10.5 mm. 



Cirri substantially as in F. Hcornuta. Cirrus i has slightly unequal 

 rami of 10 and 11 segments. Anterior ramus of cirrus ii four-fifths 

 the length of the posterior, segments 6 and 11. The caudal appen- 

 dages are broken, but evidently very short, about as in F. bicornuta. 



This handsome species is well distinguished by its large size, high, 

 two-horned contour, and the beautiful imbricated sculpture of all 

 the plates, 



F. radiata Gruvel has somewhat similar sculpture of the walls. 

 F. ratJibuniana is closely related to F. bicornuta, but there are several 



