part 3] jurassic rocks op new Zealand. 283 



side of the median depression, but these also disappear, as do the 

 median folds. Fifteen or twenty very much smaller rounded 

 ridges diverge from the beak ; but, rather more than half-way to 

 the anterior margin, they disappear, or become merged into the 

 larger angular folds already mentioned. 



Dimensions. — Length = 12 mm. ; width =: 15 mm. ; thickness 

 = 7 mm. 



Locality. — Junction of Taylor's Creek and the Otapiri. 

 Psiloceras Beds. 



Remarks. — Mr. S. S. Buckman writes, regarding the specimen 

 that I submitted to him, that it is a Rhynchonellid with conju- 

 gate or rimosiform ribbing. Very few European Rhynchonellids 

 are known from the Hettangian, and he doubts whether there are 

 any with rimose pattern. The New Zealand form is quite distinct 

 from the ffli.-rimosa Von Buch and Rh.-furcillata Theodori 

 groups of the Charmouthian-Domerian. 



Rhynchonella (Cryptorhtnchia) kawuiana, sp. nov. (PL 

 XVI, figs. 1-3.) 



Description. — Shell rather wider than long, valves inflated, 

 the dorsal considerably more so than the ventral. The greatest 

 convexity occurs about the middle of the dorsal valve. The beak 

 is small, sharp, not prominent, and projects slightly beyond the 

 ventral area ; it is not much incurved, leaving an open delthyrium 

 and foramen and a ventral area shorter than the width of the 

 shell, striate parallel to the hinge-margin, with rather foliaceous 

 lines. The dorsal valve is well and regularly rounded, and bordered 

 by steep slopes. The ventral valve has a broad median sulcus with 

 a broad fold on each side, all of which merge into the rounded 

 surface of the valve. The surface of both valves is decorated with 

 fine, regular, rounded ribs, all about equal in size, that diverge 

 from the beaks. These are cut by the concentric gi'owth-lines 

 and are prolonged, especially towards the margins, into a number 

 of solid spines. On one specimen completely detached from the 

 rock (fig. 2) the spines are missing ; on another (fig. 1) they are 

 4 mm. long ; on a third (fig. 3), where the shell has been com- 

 pletely crushed and the spines preserved in the rock, one spine is 

 9 mm. long. There is a faint, short and sharp, dorsal median 

 septum, apparently less than a quarter of the length of the 

 valve. 



Dimensions. — Length = 14 mm.; width=17 mm. ; thickness 

 = 11 mm. Another specimen is 18 mm. long, 22 mm. wide, 

 and about 14 mm. thick. 



Locality. — Totara Point, Kawhia. 



Remarks. — The occurrence of a spiny Rhynchonella in New 

 Zealand is rather remarkable, and on collecting it I was naturally 

 reminded of the genus Acanthothyris. I am indebted to Mr. 

 Buckman, however, for the suggestion that it is probably a 

 spinous development of the Indian Rhynchonella pulcherrima 



