258 FAUNA OF NEW ZEALAND. 



truncated on the hinder side. Hence they have been considered 

 as two species by Quoy and Gaimard. 



198. Pectunculus. 



Dr. Sinclair has brought me a series of specimens of another 

 species of this genus, found in a fossil state near East Cape, in 

 company with a Cardium? a Nucula, an Ostrea, and three 

 species of Univalves : two of them are probably Fusi, and the 

 other is quite a new form to any I have hitherto seen. 



"It has been stated that fossil shells are riot found in the 

 islands." Dr. Sinclair. 



199. Nucula australis. Quoy et Gaim. Voy. Astrol. 

 iii. 471, t. 78, f. 5-10. 



Inhab. New Zealand. 



Fam. MYTILID.E. 



200. Mytilus canaliculatus. Martyn, U. C. t. 78. 

 Wood, Cat. f. 47. Mytilus latus. Ckemn. viii. 167, 

 t. 84, f. 747. Dillwyn, R. S., 311. M. durus. 

 Solander. 



Inhab. New Zealand. Martyn. Cook's Straits. Dr. 

 Dieffenbach. 



This species, like the common Mytilus of the English sea, ap- 

 pears to vary in size, form, and thickness of the shell, according 

 to the locality in which it happens to be placed. 



The one variety is elongated, white within, with a purplish tint 

 on the submarginal muscular impression ; and the younger spe- 

 cimens are thin, and covered with a thin periostraca : but this 

 variety sometimes grows to a large size, as, for example, to 7 inches 

 in length, and 3 inches in width. The periostraca of these spe- 

 cimens is blackish, and bright verditer green on the edge. 



The second variety is thicker, more solid, much broader, and 

 rounded. The valves are covered with a dark-olive periostraca, 

 paler on the ventral side, purplish brown, and pearly near the 

 hinder muscular scar. Some specimens of this variety have the 

 hinder edge of the valves purplish black. 



Inhab. the North of the Thames and East Cape, New Zealand. 

 Dr. Sinclair. 



It differs from M. smaragdus of China in the young shells being 

 more ventricose, thinner, and rayed with brown. 



