BARNACLES FEOM DEEP-SEA CABLES. 299 



cilasma and I think that Pilsbry's Glyptelasma has on the whole 

 greater affinity with Darwin's genus than with Hoek's Megalasma, 

 in which the umbo of the scuta has undergone a peculiar rotation. 



Poecilasma gig as, sp. nov. 



(PL IV, fig. 4; pi. V, figs. 10-14, pi. VI, figs. 7, 8). 

 This is one of the largest species as vet known either in Poe- 

 cilasma or in Megalasma. It has also a longer peduncle than is 

 usual in either Megalasma or Glyptelasma, both of which usually 

 differ in their very short peduncle from the more Lepas-like 

 Poecilasma (s. sir.). The form of the base of the carina is charac- 

 teristic of the species. 



Capitulum. 



The capitulum is large, rather narrow, strongly compressed in 

 the tergal and carinal regions and only moderately inflated in the 

 scutal. In form it is nearly rectangular, but rendered as} 7 mmetrical 

 by the strong backward slope of the upper margin. The valves are 

 nearly smooth, white and opaque; they are separated by lines of 

 membrane and covered with a rather thick brownish cuticle, which 

 is usually torn. 



Terga. The terga are broad but have comparatively little 

 vertical depth. They are rendered quadrangular by the fact that 

 the posterior angle is distinctly truncated by the apex of the carina. 

 The backward slope of the valve is well marked, its margins are all 

 straight and its apex though not retro verted forms a very acute 

 angle. The occludent margin almost forms an angle with that of 

 the scutum, being directed backwards as well as upwards. There 

 is a well-developed triannular tooth at the outer end of the lower 

 margin on the inner surface of the left valve, but none on the right 

 valve. 



Scuta. The scuta are large, quadrangular in outline, moderate- 

 ly inflated in their basal parts, and symmetrical externally. The 

 carinal margin is arched, the others almost straight. The occludent 

 margin is, however, a little rounded below and the basal margin, 

 which is the shortest of the four, slightly concave. The umbo is 

 slightly introverted. The occludent margin is much the longest. 

 There is a well-marked groove running along the basal margin 

 above the edge. The right valve bears a blunt tooth on the inner 

 surface at the basal occludent angle. This tooth fits into the con- 

 cave surface of a short process in the corresponding position on the 

 other valve. 



Carina. The carina is of normal length. Seen from the side 

 it is strongly arched and narrow, especially above, but bears at the 

 base two short transverse processes with blunted extremities that 

 impinge on the inner ends of the basal grooves on the scuta. Seen 

 from behind the valve is quite flat in its upper half but strongly 

 carinate towards the base, at which the carina terminates in a sharp, 



E. A. Soc, No. 74, 1916. 



