part 3] jueassic rocks of new Zealand. 281 



the posterior lower margin, separating the shell-surface into two 

 parts. That in front of the ridge is gently rounded, that behind 

 it is somewhat flatter or gently curved. The posterior margin of 

 "the shell is obtusely angular, the lower margin is gently rounded, 

 the anterior margin is rather produced, and is gently rounded below 

 the lunule. The inner margin of the valves is somewhat deeply 

 pitted or crenulated. The surface is decorated with fine, closely- 

 set, rather foliaceous, concentric ribs, some of which are more 

 prominent than others. The ribs continue across the ridge on to 

 the posterior area, where they become somewhat sharper and more 

 foliaceous. 



Dimensions". — The shape is rather variable; some specimens 

 are higher than others, and have a more prominent beak. One 

 left valve is 28 mm. high, 24 mm. long, and 9 mm. deep. 

 Another, with both valves in apposition, is 22 mm. high, 26 mm. 

 long, and one valve is 7 mm. deep. Another imperfect right valve 

 is 31 mm. long and of about the same height. They all, how- 

 ever, appear to represent one species. 



Locality. — Totara Point, Kawhia, where specimens are rather 

 •common. 



Remarks. — About eight specimens were collected. The cor- 

 diform aspect of the two valves when conjoined, and the deep 

 lunule bordered by a rather sharp ridge siiggest the genus Opts 

 rather than Astarte. I cannot find any species described from the 

 Spiti Shales or elsewhere that resembles it. 



I have pleasure in naming this species after my friend, Mr. P. 

 Gr. Morgan, the Director of the New Zealand Geological Survey. 



(d) Brachiopoda. 

 B.HYNCHONELLA sp. (PL XVI, figs. 8 a & 8 b.) 



Description. — Shell subtrigonal in outline, about as wide as 

 long. The beak is small, tapering, not bent over the dorsal umbo. 

 Valves inflated, especially towards the anterior portion, the dorsal 

 more so than the ventral. The dorsal valve has a sbort median 

 fold which only continues for a short distance from the anterior 

 margin, and on either side of it a similar but rather larger fold 

 that continues about half-way to the beak. Tbese folds enclose a 

 rather shallow angular sinus on each side of the median fold, and 

 this part of the shell towards the anterior margin is raised and 

 flattened, and is bordered by steep slopes. The ventral valve has 

 a short median sulcus bordered by two short rounded folds, on 

 each side of which again is a shallow sulcus. All these occupy 

 that part of the shell which borders the anterior margin. There 

 is a broadly rounded fold on each side forming wing-like projec- 

 tions, and a broad, shallow, rounded, median fold which continues 

 nearly to the beak. There are sharp dental plates in the ventral 

 valve, and a short median septum in the dorsal valve. 



Dimensions. — Length = 19 mm.; width=20mm.; thickness 

 = 10 mm. 



x2 



