294 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 42. 



Base calcareous, very tliin in the center, thicker and sohd toward 

 the edges. Plates of the walls solid, without radii. The plates are 

 white, clouded with pink near the summits of the side-plates and 

 carina, the parietes covered with a very thin yellowish cuticle; oper- 

 cular plates yellow, pinldsh toward their apices. The orifice is large, 

 piriform, toothed; the alee have arched, minutely serrate upper edges. 

 The sheath is very short, and its lower edge does not overhang. 

 Rostrum and rostral latera separated by inconspicuous linear sutures. 

 Scutum narrow, its greatest width less than half the length, convex 

 outside, with sculpture of smooth, wide, and even growth ridges parted 

 by deep, narrow grooves. The articular ridge is very low, and there 

 is no adductor ridge. The tergum has an extremely short spur and 

 no trace of a longitudinal furrow. There is a liigh articular ridge, 

 and a series of short teeth in place of the depressor muscle crests. 



Greatest diameter of base, 16.5 mm.; height of carina, 13.6 mm. 



ACASTA PECTINIPES, new species. 



Type-specimen.— Cat. No. 43473, U.S.N.M. 



Type-locality. — Albatross station 5276, near Malavatuan Island, 

 off southern Luzon, 18 fathoms. 



The barnacle has a deep base, rather weakly striate. The plates 

 of the wall are inflected above, with sculpture of prickly longitudinal 

 threads. Paries of carina-lateral plate reachmg to the base, but 

 extremely narrow, about one-seventh as wide as the rostro-lateral; 

 radii and alae quite narrow. There are narrow but distinct slits 

 bridged by membrane between the bases of the plates. Scutum 

 regularly sculptured with ridges of growth, the basal margin approach- 

 ing the occludent margin in length. Tergum very short, with can- 

 cellated external sculpture and an extremely short spur, about one- 

 third the width of the basal margin. 



Length of walls and base, 8 mm.; carino-rostral diameter, 6.2 mm. 



ACASTA IDIOPOMA, new species. 



Type-specimen.— CaJi. No. 43466, U.S.N.M. 



Type-locality. — Albatross station 5254, Gulf of Davao, Mindanao, 

 21 fathoms. 



Walls white. Base deeply bowl-shaped; parietes of carina-lateral 

 plate more than half as wide as rostro-lateral; no apertures between 

 the bases of the wall-plates, which do not converge upward. Scutum 

 strongly striate longitudinally, with a carina marking off the occludent 

 third, which protrudes as a rounded lobe or scutal spur beyond the 

 rest of the lower outline. Tergum having a short triangular spur 

 united with the adjacent border of the plate. 



Greatest diameter of the wall, 7.2 mm. 



Readily known by the peculiar opercular plates. 



