129 



zoologica et pal^ontologica 



Miscellanea, 

 chiefly belating to south aitstkalia. 



By Professor Balph Tate, Assoc. Lin. Soc, F.G.S., Corr. 

 Memb. Acad. Sc, Philadelphia, Boy. Soc. Tasmania, &c. 



ON A NEW GENUS OE EOSSIL LAMELLIBEANCHIATA. 



Eamilt Mactrxd^:. 



Genus Zenatiopsis, nov. 



Etymology. — Zenatia, a genus of Mactridse ; and opsis, like. 



Type. — Zenatiopsis angustata, nov.- spec. Miocene. Australia. 



Shell equivalve, inequilateral, oblong ; umbo anterior, 

 supported internally by a thick rib, extending, with a slightly 

 backward inclination, balf way across the vah r e ; narrowly 

 gaping at botb ends ; cartilage plate prominent ; cardinal 

 teeth distinct, no lateral teetb ; pallial sinus deep, borizontal. 



Zenatiopsis combines the form and internal appearance of 

 Macliccra with the hinge characters of Zenatia ; the resemblance 

 of the only known sp'ecies to Zenatia acinaces is very great, but 

 the presence of an umbonal rib, like that in Maclicera , is a 

 valid reason for not regarding it as congeneric therewith. It 

 is distinguished from Vanganella, as Zenatia is, by the dentition ; 

 whilst the anterior divergent rib of Vanganella supports the- 

 cartilage plate with which it is confluent ; the internal rib of 

 Zenatiopsis is an umbonal support, and arises from beneath the 

 cardinal teeth. 



The anterior adductor scar is close up under the hinge line 

 as in Zenatia, and is bounded on the posterior side by the 

 umbonal rib. 



Zenatiopsis angi'stata, nov. spec. PI. v., figs. 6a, 6b.— 

 Shell thin, compressed, narrowly oblong, back slightly convex ; 

 anterior end very short and rounded, posterior long rounded. 

 Umbo small, apiculate. Dorsal and ventral margins nearly 

 parallel. Surface shining, marked by a few slender plications 

 of growth, and numerous fine coincident striations. 



Dimensions of a large example from the "Upper Murra- 

 vian": — 



Total length T8 inch 



Length of anterior side ... "25 inch 



Height ... ... ... ... *6 inch 



