216 DE. C. T. TEECHMAXX OX [vol. Ixxiil, 



greatly in width of the hinge-hne, in which the dental plates join 

 the median septum. Zugmayer^ describes several such ^pirif evince 

 from the Alpine Rhsetic, and includes them in his group of 

 Dimidiata?, separating them from the genus Cyrtina^ in which 

 this septal and dental peculiarity also occurs, apparently on account 

 of their concave and uncovered delthvrium. The Cyrtiniform 

 septal arrangement is apparently a phylogerontic feature, and 

 seems to have arisen independently in several phyla of Spiriferincd 

 Hector's subgenus includes forms which closely resemble the Alpine 

 Rhaetic iipiriferina suessi and Sjj. austriaca, and new forms 

 which I have named Sp. neJsonensis and ^p. otamitensis. The 

 early appearance of these forms in the Xew Zealand Trias is a 

 remarkable feature. 



Clai'igera represents a group of specialized bisulcate Spirigerids 

 the affinities of which are discussed later on. I have considered it 

 advisable to rename this group, and have called it Hectoria. 

 Hector's description was published A\'ithout any illustrations, and 

 his subgeneric name closely resembles that of Claviger given to 

 2i group of the Melanias. 



Haloeella zeala^'dica, sp. nov. (PI. XXIII, figs, lr^-3.) 



Beak prominent, the hinge-line sloping rapidly away fi-om it on 

 each side, giving the shell a subti-iangular outline. The delthy- 

 rium is triangular and insunken. In the ventral valve is a broad 

 median sulcus with a flattened Hoor, on Avhich two (or, in some spe- 

 cimens, four) small rounded folds occur, and continue from about 

 a third to half of the distance to the beak. The sulcus is bounded 

 on each side by a broad rounded fold, which continues about half- 

 Avay to the beak, and two similarly rounded, but much shorter, 

 lateral folds on each side. The dorsal valve has a broad median 

 depression, but it is rather flattened than sunken, and bears two (or, 

 in some specimens, three) narrow rounded folds on it, which continue 

 for only about a third, or rather more, of the length of the shell 

 from the anterior margin. The median depression is bounded 

 by two broad, rounded, lateral folds which reach about halfway to 

 the beak, and there are two more rounded but shorter lateral folds. 



Dental plates are well developed in the ventral valve, and in the 

 dorsal valve there is a sharp median septum Avhich extends from 

 the beak about halfway to the anterior margin. Growth-ridges 

 are well marked, but widely spaced. 



This species varies somewhat in shape and dimensions, and in the 

 number of secondary ribs on the median sulcus ; some specimens 

 are wider, and have a less prominent beak than others. One 

 example is 16 mm. long and 15 mm. wide ; another is 13 mm. long 

 and 13 mm. wide; a third is 13 mm. long and 15 mm. wide. 



Locality and horizon. — It is common in the Kaihiku 

 Beds at all localities. I collected many casts and impressions at 



^ Bibliography, 52, 



