82 



The transverse edging, though common in the Mesozoic Trigoniee, is not 

 found in the recent species." The sculpture of this shell leads to the as- 

 sumption that in it we have a continuation of the style of ornamentation 

 peculiar to forms of the genus belonging to the secondary rocks into the 

 succeeding strata of the Tertiary system. It will be seen, too, that T. 

 semiundulata has a wider range geographically than any other, being 

 recorded from South Australia, Victoria, Tasmania, and New Zealand, 

 and also that it has not been found in a later division of the Cainozoic 

 period than the Upper Miocene. It has been found in the 



Miocene— Bird Rock Bluff, Victoria {McCoy), Muddy Creek, Ha- 

 milton, Victoria {Tate), Gawler, South Australia {Tate), Table Cape, 

 Tasmania (B. M. Johnston, Pro. Ryl. Soc, Tas., 1876). 



Upper Miocene — Arramoa, New Zealand {Hutton, Cat. Ter. Mol., 

 N.Z„ 1873). 



5. T. Howitti (McCoy), 1. cit., Decade III., t. 27, f. 3, pi. 31, 



1876. 

 Loc. Sandy marl, Jemmy's Point, near the entrance to the Gipps- 

 land Lakes. 



6. T. acuticostata— (McCoy) — 1. cit. Decade II., t. 19, f. 1-2, 



pi. 21. 



" T. acuticostata,'" remarks the author, " is easily distinguished from 

 the recent species by the remarkable compression of the ribs into acute 

 angular ridges, and from the same cause the spinous tubercles do not form 

 the broad blunt transverse tubercles which they do in the recent species.'' 

 Since the above remarks were written some years a^o, for T. acuticostata 

 appears to have been the earliest Tertiary species discovered, it has been 

 found living on the south-eastern coast of Australia. The localities from 

 which it is recorded are : — 



Miocene. — Muddy Creek, Hamilton, Victoria (McCoy). Cliffs, 

 River Murray, North- West Bend (Tate). Casts, probably of T. acuti- 

 costata, occur in beds of the same age' at Tickera, Yorke's Peninsula, and 

 at Aldinga, South Australia (Tate). 



Pliocene. — Mordialloc, Hobson's Bay, Victoria. 



7. T. pectinata, Lk. 



Upper Miocene. — Hampden, New Zealand (Hutton, Cat. Ter. Mol. 

 N.Z., 1873.) 



From the above-mentioned observations we obtain the following 

 table of the geographical and geological range of the Trigonia in 

 Australia : — 



