MOLLTJSCA OF THE ' CHALLENGER ' EXPEDITIOir. 39 



there is a blunt reverted tip, but uo embryonic shell ; the surface 

 is rayed with five smooth, rounded, unequal riblets, Scul^tttre. 

 Longitudinals — from the top proceed radiating riblets, which are 

 regular, delicate, well rounded, raised and unequal, a few being 

 a little stronger than the rest which, to the number of two to four, 

 closely occupy the intervals. Spirals — these are microscopic, 

 rounded, close-set, and very faint. Colour : under the strongish, 

 hard, membranaceous, pale brownish epidermis the shell is por- 

 cellaneous white. Apex : the embryonic apex has been removed, 

 and a scarred plug at the very top of the back slope fills the hole 

 it left. Margin thin and broken, and overlapped by the epidermis. 

 Inside porcellaneous, delicately fluted, open to the apex, with a 

 Btrongish horse-shoe scar, with two oval muscular impressions, 

 and the prominent head-scar shaped like that in I'atella, only 

 somewhat larger in proportion. L. 0'13. B. 0"07. H. 0'07. 



I dissected the animal of this species with great care, but not 

 much satisfaction, the specimen being extremely small and neces- 

 sarily somewhat damaged by preservation in spirit. No eyes 

 could be seen ; but as their absence on the surface is sometimes 

 due to a power of internal withdrawal, I looked for them care- 

 fully during dissection, but in vain. There were no appendages 

 to the side of the foot or on the mantle-edge, a feature on which 

 Mr. Dall dwells in establishing the genus. He describes the 

 branchia as a single asymmetrical gill, but plumose. In the 

 ' Challenger ' species there was no appearance of a plume, but a 

 somewhat stumpy finger-shaped process projected backward from 

 the lower right side of the neck ; and from the side of this pro- 

 cess another, very much smaller, issued in the same direction. 

 The surface of both these (and of them alone) was finely tessel- 

 lated or beaded ; and in each bead there seemed to be the loop 

 of a blood-vessel. The dentition is, as Mr. Dall observes, very 

 like that of Scutus australis, Quoy, given in Grray's ' Gruide,' 

 p. 163, so far, that is, as general arrangement and relation is con- 

 cerned ; but in Cocculina angulata the centre tooth is higher and 

 narrower, with a much smaller cusped point, and is shouldered at 

 either side ; the three following laterals on either side in form and 

 position are like those given by Grray at p. 190 (not p. 172), 

 f. 103, as those of Lepeta cceca, only that the inmost one has three, 

 the second two, and the third one cusp. Thus far, therefore, 

 Gray's figure of Lepeta cceca, p. 190, agrees better, so far as it 

 goes, with the toothing of Cocctdina angulata ; but beyond the 



