45 



Right valve with a long lanielliforni tooth on each side ; left 

 valve edentulous ; cartilage-pit posteriorly inclined. 



Antero-posterior diameter, 6-5; umbo- ventral diameter, 4; 

 transverse diameter, 2-25. 



Habitat. — St. Vincent Gulf, numerous examples dredged by 

 Dr. Verco. 



Affinities. — The dentition is that proper to Rhinomya, Adams, 

 = Section G., Smith. Hitherto this section has been unrepre- 

 sented in the Australian fauna, as the R. rugata recorded by 

 Angas is not the species of Adams ; it belongs to Section F, 

 and has been described by Smith as C. Brazieri. 



In form and sculpture it resembles C. Brazieri, except that 

 the rostrum is shorter (perhaps not a constant character). This 

 general resemblance renders it doubtful if the South Austra- 

 lian shell is distinct from Rhinomya rugata, Adams, inhabiting 

 Japan, except that "oblonga," "concentrice confertim lirata," and 

 " liris corrugates" do not well apply. 



Cuspidaria trigonalis, Tate, 1897. 



Subtrigonous, produced posteriorly into a short triangular 

 rostrum ; ventricose, white, ornamented with concentric 

 lamellae ; the lamellae of the left valve are distant, thin, elevated, 

 wider than the interstitial sulci ; those of the right valve de- 

 pressed and separated by linear sulci. 



Right valve with a lamellar tooth on each side, left valve with 

 a stout denticle in front of the hinge-notch ; cartilage-pit deep 

 and subtriangular in outline. 



Antero-post. diameter 5-5, excl. rostrum 4-25 ; umbo-ventral 

 diameter 4, transverse diameter 4. 



Habitat. — Investigator Straits, dredged in 15 fathoms by Dr. 

 J. Verco. 



Remarks. — Of the four known examples, three are left valves 

 and one is a right valve ; they have the same shape, but as the 

 ornamentation of the opposite valves is different it is possible 

 that two species are represented ; yet there is nothing incom- 

 patible to the opinion that the difference of ornamentation is one 

 of degree, though it may be, we have here a species with the 

 opposite valves dissimilarly ornamented. 



The dentition of C. trigonalis is that of Section N., estab- 

 lished for C. Tasma7iica, from which species it differs by its con- 

 spicuous cardinal denticle, shape and ventricosity, and thus also 

 from C. simulans. Indeed, it is remarkable among congeners by 

 its subtrigonal outline and umbonal inflation. 



Corbula compressa, Verco, Tr. Roy. Soc, S. Aust., XX. p. 

 230, t. 8, f. 2, 1896. 



Myodora corrugata, Verco, op. cit. p. 229, t. 8, f. 1, 1896 (non 



