127 



The differences between the two species, however, become more 

 accentuated as the neanic stage is reached in each case, aad with 

 the adults the separation is well marked. 



In general, it may be stated that the shell is small and turri- 

 culate ; but the costis are closer together and more striate than 

 in the last-mentioned species. Peculiar characters are the com- 

 paratively sharp angulation in the vicinity of the suture, and the 

 absence of nodosities on the anterior portion of the body-whorl, 

 which is occupied by prominent transverse threads. The number 

 of columellar plications varies from three to four ; but the material 

 at the writer's disposal is not abundant enough to enable their 

 development to be traced. 



Dimensions. — Length 5'5mm. ; breadth l"75mm. ; length of 

 aperture 2 mm. 



Form, and Loe. — Eocene : Muddy Creek, Yictoria. 



G. 9375. Three specimens. Purchased. 



Uromitra semilsevis, Tate (sp.). 



1889. Mitra [Pusio] semihevis, Tate, Trans. Eoy. Soc. South Aust. vol. si. 



pp. 136, 143, pi. v. fig. 9. 

 1893. Mitra semilicvis, Tate and Dennant, id. vol. xvii. pt. 1, p. 220. 



Shell very small, fusiform, narrow ; protoconch. similar to that 

 of W. exilis and TI. leptalea ; whorls three in number, slightly 

 convex, ornamented by obtuse longitudinal costae on the earlier 

 whorls, and these become comparatively inconspicuous on the 

 body-whorl of the adult, being reduced to mere undulating 

 corrugations ; the suture is slightly marginate. The last whorl 

 is much attenuated and drawn out anteriorly ; aperture elongate, 

 outer margin lirate within, columella with four plications, which 

 have the appearance of being continued as spiral ridges round 

 the anterior portion of the body-whorl. 



The obtuse, rather distant costos on the earlier whorls, the 

 comparatively smooth body-whorl of the adult, and the peculiar 

 anterior prolongation, are features enabling U. semilcevis to be 

 readily distinguished amongst its congeners. 



Dimensions. — Length 5 mm.; breadth 1-75 mm. ; length of 

 aperture 2-75 mm. 



Form, and Loe. — Eocene : Muddy Creek, Yictoria. 



G. 9344. Three examples of the adult. Purchased. 



