58 G. T. Treclimann — Age of the 



the margin so that when the two valves were together a byssal 

 opening was produced. The surface is ornamented with a series of 

 broad and very irregular concentric furrows and ripples. 



The New Zealand specimens ' are hardly sufficiently well preserved 

 to justify a specific determination, but they seem to agree in most of 

 their features with Aphanaia Ifitchelli, F. McCoy sp., of the Upper 

 Marine Permo-Carboniferous of various localities in New South 

 Wales. The larger species, A. gigantea, de Kon., seems to differ 

 in the boat-like shape of the larger valve and the greater obliquity of 

 the hinge-line. 



Platyschisma sp. (PL V, Fig. 9.) 



The shell has a depressed spire and consists of four or possibly five 

 whorls, which are smooth and rounded and increase rapidly in size. 

 The last one is rather angular below, and the shell structure is fibrous. 

 Owing to its poor state of preservation the growth-lines can scarcely 

 be detected, neither could the umbilicus be clearly seen, but after 

 examining the fragments of another specimen I think that there was 

 a shallow umbilicus. Both in outward shape and in the fibrous 

 structure this shell has every appearance of identity with Platysehisma 

 of the Permo-Carboniferous marine beds of New South "Wales, and 

 seems to agree more closely with P. rotunda, 2 Kth., than with the 

 more common P. oculus, Sow. 



Locality. — Maitai Limestone, upper end of the Wairoa Gorge, in the 

 side of the stream where the Roding joins the Wairoa River. The 

 figured specimen was collected by Dr. Thomson. I found another 

 close to the first one, but in a still poorer state of preservation. 



Pleurotomaria or Mourlonia sp. (PL V, Fig. 10.) 

 A piece of limestone full of fragments of the prismatic bivalve 



shows on its weathered surface the outline of a small Gasteropod 



having four keeled whorls. The keel passes round the middle of the 



last whorl and lies above the suture in the penultimate whorl. 



The shell is weathered away, but in outline suggests a small 



Mourlonia. 



Various small Pleurotomaria are recorded from the Permo- 



Carboniferousof Australia and the Salt Range, but none seem quite 



so strongly keeled as the present form. 



Strophalosia sp. (PL V, Figs. 4, 5.) 



Hector records Productus brachythcerm among the fossils obtained 

 from the Maitai Limestone, but on examining the specimens 



1 I may here remark that in consequence of the occurrence of annelid-like 

 tubes in the Maitai Limestone similar to those in the Mt. Torlesse beds and 

 in the Yakutat slates of Alaska I suspected that the genus Inoceramya, Ulrich, 

 from the latter beds might be similar to the New Zealand shell. But on 

 looking up the description of this shell in the report of the Harriman Alaska 

 Expedition, I found that it is quite different and possesses a series of vertical 

 ligamentary pits and is undoubtedly closely related to Inoceramus. The 

 Yakutat slates seem to be of Liassic age. 



2 Jack & Etheridge, Geology and Paleontology of Queensland, 1S92, p. 286, 

 pi. xv, fig. 6. 



