go PHYLOGENY OF FUSUS AND ITS ALLIES. 



The protoconch and young conch of this species and of H. 

 caloosacnsis are ahnost absohitely identical. The early whorls are 

 slightly less concave than in some specimens of H. caloosacnsis but 

 more concave than in others. On the fourth whorl the ribs disappear 

 and the spirals become fainter, the whorls at the same time changing 

 from a subangular to a rounded contour. The fifth volution of. this 

 species is rounded while the same in H. caloosacnsis is still angular with 

 strong spirals. Intercalated spirals appear in the third volution, and 

 in the sixth and later volutions they have reached a uniform size with 

 the primary ones and no new ones appear. 



A very old specimen of this species has the spire somewhat 

 elongated and the spirals are sharp, with very fine intercalated ones 

 on the last whorl. The lirse of the inner lip and the posterior canal 

 are of the type which occurs in H. caloosacnsis, the outline of the 

 aperture being, however, more oval. The aperture of H. caloosacnsis 

 is strongly contracted just below the body whorl. 



For further description see reference given above. 



Localities: Duplin County North Carolina (Nat. Mus. 112381); 

 Magnolia, Duplin County, North Carolina (Nat. Mus. 1 14549, 1 14550, 

 also at Wag. Free Inst.) ; Natural Well, Duplin County, North 

 Carolina (Nat. Mus. 114548). 



Horizon: Miocene (?) (If H. caloosacnsis is Pliocene, then H. 

 eqiialis is probably not Miocene, and should normally occur with if not 

 later than H. caloosacnsis. The Pliocene age of this latter species is 

 accepted by all authorities.) 



HEILPRINIA EXILIS (Conrad). 

 1832. Ficsus exilis Conrad, Foss. shells Tert. Form. N. Am., p. 17, pi. 3, fig. 2. 



This is another modification of the type of the genus. The proto- 

 conch has not been observed, but it is most probably of the same type 

 as that of H. caloosacnsis. The shoulder in the earliest whorl observed 

 is concave, with three strong spirals at the angle. The lower of these 

 spirals is barely visible above the suture, the succeeding whorl covering 

 its lower half. The first spiral on the shoulder next above the peripheral 

 spirals is strong and sharp. The next one is weaker. This prominence 

 of the first of the shoulder spirals gives the whorl a rounded appear- 

 ance. This feature becomes more accentuated as the shell grows older. 

 Ribs continue through five whorls, then quickly disappear and only 

 strong, subequal and sharp spirals remain, between which are single 

 finer ones. The primary spirals are about equal on the shell, there 

 being seven and later eight of these between the sutures with inter- 

 calated secondary spirals between all. The outline of the aperture 

 is more oval still than that of H. cqualis. This latter species is inter- 

 mediate between H. c.xilis and H. caloosacnsis. In H. c.vilis the aper- 



