The Austral RhynchoneUaeea. 



IH\ 



species tends to be greater in length than width, although there ar« 

 exceptional cases where it is slightly wider than long. The beak is 

 much higher than in T. coelata, and the deltidial plates are conjunct. 

 The plication is at once seen to be much finer in character than in the 

 Victorian species, T. coelata, which in some other respects it resembles. 

 It will be appropriate here to append a synopsis of the average num- 

 ber of plicae which we hare counted on the ventral sinus of the 

 principal species of the genus Tegiilorhyncliia. 







Average 



number 



of 







Species. 



plicae 



on 



sinus of 



ven- 



Range in Time. 









tral valve. 







1\ 



p'atago7iica, Ihering 

 sp. 





12 



to 15 





Oligocene or Miocene 

 (Patagonia) Buenos 

 Aires. 



T. 



squamosa, Hutton, 

 sp. 







10 





(?) Oligocene, New 

 Zealand. 



T. 



coelata T. Woods, 

 sp. 







8 





Miocene. Victoria. 

 South Australia and 

 Tasmania. 



T. 



thomsoni, sp. nov. 







6 





Miocene. Tasmania. 



T. 



nigricans, Sow, sp. 







4 





Upper Miocene to Re- 

 cent. New Zealand. 



Pedicle foramen, long-ovate and well elevated above the cardinal 

 margin, the height being occasioned by the conjunct character of the 

 deltidial plates. The elevation of these plates in some specimens is 

 accompanied by a low, crescentic cavity between the cardinal margins 

 of the ventral and dorsal valves. Viewed in profile, from the anterior 

 .aspect, the tegulation in T. squamosa seems to be largely confined 

 to the ribs, whereas in T. coelata the tegulation is continuous over 

 the ribs and intercostal areas. The discrepant growth-lines in T. 

 squamosa are not so strongly marked as in T. coelata, and from that 

 we may infer that T. squamosa is the older type, compared with 

 T. coelata, the latter connecting with T. nigricans in this particular 

 character of tegulation. 



Occurrence. — (?) Oligocene (Ototaran stage). Broken River, New 

 Zealand. 



Miocene. Cockburn Island, Graham Land, Antarctica. 



-Tegulorhynchia coelata, (McCoy, MS.), T. Woods, sp. 



(PI. I., figs. 3, 4; pi. II., figs. 17, 20; pi. III., fig. 27.) 

 Rhynchonella coelata (McCoy, MS.), T. Woods, 1878, p. 77. 

 Rhynchonella squamosa (non Hutton), Tate, 1880, p. 32, pi. 

 IX., figs. 9a, 1). 



