NO. 1904. NEW BARNACLES FROM THE CHINA 8EA—PILRBRY. 293 



produced. Rostrum having the beak removed some distance from 

 the scutal border, the intervening area radially ribbed, the ribs ter- 

 minating on the scutal border, where they interlock with those of the 

 scutum; basal edges of the plates of the wall thin and simple. There 

 is no myophore in the fixed scutum. 



Greatest carino-rostral length, 7.5 mm.; breadth, 5.4 mm.; height 

 of fixed tergum, 4 mm. 



This is a very distinct species, by reason of the shape of the rostrum, 

 in which the summit stands remote from the scutal margin as in 

 V, nexa and T^. Icaehleri. 



PACHYLASMA DARWINIANUM, new species. 



Type-specimen. — Cat. No. 43465, U.S.N.M. 



Type-locality. — Albatross station 51 6S, Sulu Archipelago, Tawi 

 Tawi group, 80 fathoms. 



A species living upon and partly embedded in a hard sponge. 

 Walls solid, base wholly membraneous. The walls form a low cone, 

 %vith rather large, deeply toothed aperture and are dull red, fading 

 toward the rostrum, which is pale or whitish. The plates are strong, 

 \vith the parietes smooth except for a fine rugosity; the alae broad, 

 regularly striate vertically, with oblique, minutely crenulate summits. 

 The scutum is half as wide as long, convex externally, with sculpture 

 of crowded, strongly crinkled growth ridges. Internally there is a 

 low articular ridge and no adductor ridge. The tergum is triangular, 

 without a spur, striate longitudinally on the carinal half, having a 

 low, rounded rib, bounded by depressions on the scutal half. Inter- 

 nally there is a high, short articular ridge, and UTegular crests for the 

 depressor muscles, projecting in jagged teeth below the margin. 



Greatest diameter of the wall, 18 to 20^ mm. 



Strikingly unlike all known species in the sculpture of the scutum 

 and the shape of the tergum. 



Pachylasma darwinianum agrees with P. giganteurn (Philippi), P. 

 crinoidopMlum Pilsbry, and P. chinense, new species, in having con- 

 spicuous aliB on the carina, carino-lateral and medio-lateral plates, 

 thereby differing from P. aura ntia cum. Darwin, in which the carino- 

 lateral and medio-lateral plates unite in a simple, linear suture. It 

 differs from all other known species, except P. crinoidophilum, by 

 having the base wholly membraneous. 



The species of Pachylasma now known are very distinct from one 

 another. So far as we know, all are local in distribution, and appar- 

 ently rare. P. darwinianum is known by several specimens cut out 

 of a very dense, hard sponge. 



PACHYLASMA CmWENSE, new species. 



Type-specimen. — Cat. No. 43471, U.S.N.M. 



Type-locality. — Albatross station 5301, latitude 20° 37' N.; longi- 

 tude 115° 43' E., China Sea, near Hongkong, in 208 fathoms, on the 

 scutum of a living ScalpeUum steamsii. 



