110 



about one-third, and the shape of their aperture, apart from the emargi- 

 nation, ig. elliptic-ovate, the width being greatest at the base. Mr. Meek, 

 however, says that the dorso-ventral diameter of the whorls in A. 

 Newherryanus is nearly or quite equal to their transverse breadth. 



3. The umbilicus of this species is proportionately wider than it is in 

 A. complexus, var. Suciensis, and exposes more of the inner whorls. 



4. Besides being regularly ribbed, the surface of A. Newherryanus is 

 marked, at distant but somewhat regular intervals, by transverse, swel- 

 ling rims, the remains of former lips. In a specimen not quite five inches 

 in diameter there are seven of these in the outer whorl. They may be 

 easily distinguished from the ribs by their much larger size, also by the 

 circumstance that they are convex on the inner as well as on the outer 

 surface of the test, which is evinced by the broad grooves they leave on 

 the east. 



Of the twenty-one specimens collected by Mr. Eichardson only two 

 shew the septation at all. One of these is a water-worn cast in which 

 many of the finest ramifications of the sutures are eff'ai'ed, and the other 

 is a fragment of a very young individual, whose lobes and saddles are 

 partly covered by the test. Nineteen have the flattened whorls, the 

 comparatively wide umbilicus, and the periodic arrests of growth 

 characteristic of A. Newherryanus, but two large, though imperfect 

 individuals, both from North-West Bay, V. I., ditfer from the rest in 

 some rather important particulars. The whox-ls are not nearly so much 

 flattened at the sides, their height and width being almost equal : the 

 umbilicus has slopingly convex sides and the ribbing appears to be 

 sharper than in average specimens. Still, the umbilical opening of these 

 sbells is wider than in A. complexus var. Suciensis, more of the inner whorls 

 are exposed than in that species, and the thickening of the lip at regular 

 inteiwals, (traces of which, at least, are alwaj'S to be seen in the true A. 

 Newherryanus) though more obscure than usual in these two specimens, is 

 nevertheless perceptible. 



Mf. Meek's description of this species leaves nothing to be desired as 

 regards accuracy, so far as it goes, but it was based on a single worn cast 

 not more than two inches and a quarter across, and consequently does 

 not express the whole of the characters of the shell. When fully grown 

 A. Newherryanus must have attained to a very large size, for a specimen 

 from- the Sucia Islands measures eighteen inches across, and it consists 

 entirely of septate whorls. With an increase of age, after a certain point 

 the ribs and other surface markings gradually become wider apart, flatter 

 and feinter, until at last they disappear altogether. In the large Sucia 



