SEMICASSIS. 199 



Protoconcli of two and ti luilf smooth, depressed turns, gradually 

 increasiug in size from the initial portion, abruptly separated from 

 the succeeding whorl. The cancellate ornament, so well developed 

 OQ the hody-whorl of the adult, commenced to form in the earliest 

 part of the brephic stage. Spire elevated, subangulate at the 

 shoulder ; suture accompanied by a small, acute ridge ; aperture 

 oval-oblong, obtuse posteriorly, and rounded in front; outer margin 

 thickened, reflected, and dentate within ; columellar expansion 

 smooth, forming a thin plate anteriorly ; columella twisted, and 

 having several irregular plications, with here and there a tubercle 

 anteriorly. 



A characteristic feature of the shell is the fine cancellate 

 ornament. 



Mr. G. B. Pritchard has indicated that S. transenna, Tate, is a 

 synonym of this species as above shown. As Mr. Tenison-Woods 

 did not give a figure of S. sufflata, the present writer cannot control 

 the matter; but the description given by its author certainly 

 appears to bear out Mr. Pritchard's views. 



Dimensions. — Length 29 mm.; breadth 17 mm.; length of 

 aperture and canal 19 mm. 



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



G. 4179. Several examples of the adult. 



Presented hy John Bennant, Esq. 



G. 5505. An example of the adult. Purchased. 



Semicassis muelleri, Tate, 



1889. Scnucaxsis muelleri, Tate, Traus. Eoy. Soc. South Aust. vol. xi. 

 p. 167, pi. vii. fig. 9. 



This species diff'ers fi'om the preceding principally in the absence 

 of cancellate ornament, its aperture being broader and the whole 

 shell more ventricose. The whoiis have bold spiral bands of 

 unequal size crossed by fine growth-lines which lead to cancellation 

 accompanied by dentate elevations on the bands referred to. This 

 ornament is almost entirely confined to the area between the 

 subangulation of the shoulder of the body-whorl and the suture ; 

 the latter is bordered by a granulose lineation best developed in 

 tlie young state. The body-whorl has regularly-spaced growth- 

 lines with obsolete spiral linealions in front of the subangulate 



