part 3] THE TRIAS or ]S'ew zealaxd. 21 L 



Kemarks. — I was undecided at times whether to regard this 

 shell as a Trigonia or a 3£yophoria, but have finally come to the 

 conclusion that it is a 3Iyophoria. The striation of the hinge- 

 teeth alone does not apparently make it a Trigonia, although thfr 

 very slight but definite posterior inclination of the beaks in some, 

 if not all, of the specimens is suggestive of Trigonia. 



Two Triassic Trigonim have been recorded. Bittner in 1895 

 described Tr. gaytani (Klipsteinj from the St. Cassian Beds, 

 and placed it in the group of Costatse ; and J. Boehm in 1903 

 described a very small form (Tr. margaritifera) from the Upper 

 Trias of Bear Island in the Arctic Circle. 



Myophoeia otamitensis, sp. nov. (PI. XXII, fig. 8.) 



Shell rather small, beaks situated slightly behind the median 

 line, medially directed. Margin rounded in front and below, 

 slightl}^ angulated behind, but not j^roduced. A raised keel, bearing- 

 seven or eight coarse nodes, passes from behind the beak to the 

 lower posterior margin. Behind this keel a shallow sulcus passes- 

 down the flank of the shell, rather more than halfway towards its 

 posterior margin. The flank is decorated with raised tubercles of 

 irregular size. In front of the keel, and almost adjoining it, is a 

 fine raised ridge ; in front of this are six very much more prominent 

 ridges, which are cut by the concentric growth-furrows into a 

 series of prominent rounded nodes. The young shell bears a series- 

 of concentric wavy ridges. Length = 18 mm. ; height = 15 mm. 



Locality and horizon. — The holotj'pe is an excellently pre- 

 served specimen (with both valves and the test preserved) that I 

 collected in Bed c at Otamita, Hokonui Hills. Carnic. 



Fragments of casts, apparentl}^ of this shell, are common in the 

 decomposed felspathic sandstones of the Carnic, near Grore, in the 

 Hokonui Hills, and other localities. A form which may be 

 identical occurs also in Noric beds, but is generally very badly^ 

 preserved. 



Myophoeia heslijS^gtonei^sis, sp. nov. (PI. XXII, fig. 9.) 



Shell small and finely sculptured, rounded in front, gently 

 rounded below, but angulated at the lower posterior portion wherfr 

 the ridge joins the margin. An acute raised ridge passes from 

 behind the beak to the lower posterior margin, in front of which 

 there is a wide sulcus. The middle part of the shell bears six or 

 seven faint radial ridges, which become progressively fainter as they 

 approach the anterior margin. These are crossed by a series of 

 very regular concentric ridges and furrows forming a series of raised 

 points. Behind the ridge the flank is decorated with fine raised 

 points. Length := 7 mm. ; height zz 6 mm. 



Locality and horizon. — Mount Heslington, south of the 

 Wairoa Gorge. Carnic. The holotype consists of a piece of hard 

 felspathic sandstone belonging to the New Zealand Geological 

 Survey, having three or four casts on its surface, from which I made- 

 a gutta-percha squeeze. 



