148 Transactions, — Zoology, 



Art. XVIII. — On the Fresh-water Lamellibranclis of New Zealand. 



By Professor F. W. Hutton. 



{Read before the Philosophical Institute of Canterbury, 13i7i October, 1881.] 



Plate II. 



UNIONIDiE. 



In the second volume of Dr. Dieffenbach's " Travels in New Zealand " 

 (London, 1843) Dr. Gray described two species of Unio, brought to England 

 by Dr. Dieffenbach and Dr. Sinclair. These he called U, menziesii and U. 

 aucklandica. They are distinguished by the first being high and compressed, 

 the posterior lateral teeth crowded, the inner anterior tooth of the right 

 valve large, thick, ovate, rugose, and the other teeth small and compressed. 

 He also distinguished a variety which was more elongated, and rounder 

 behind, and the posterior lateral teeth not so elevated. The second species 

 is thick, the cardinal teeth low, blunt, oblique, and the posterior lateral teeth 

 laminar, and far off. These species were afterwards figured by Eeeve in his 

 Conchologia Iconica. 



In 1850 Mr. A. Gould published in the " Proceedings of the Boston 

 Society of Natural History" a description of another species from Auckland, 

 under the name of U. lutulentus, and this was afterwards figured in the 

 " Mollusca of the United States Exploring Expedition," and also by Eeeve. 

 I have not seen Gould's description or his figure, but, according to Eeeve, 

 the shell is rudely longitudinally plicated. 



In the " Malakozoologische Blatter" for 1861 Dr. Dunker described a U. 

 hochstetteri, brought to Germany by Dr. v. Hochstetter from the Eiver 

 Waikato and Lake Taupo, distinguished by being " very indistinctly sub- 

 verrucose in the middle. This also is figured by Eeeve, and shows a 

 shell very much truncated behind, the length being only 1-4 times the 

 height. 



In the " Mollusca of the Voyage of the Novara" Dr. Dunker also described 

 and figured a U. zelebori. This is rather an elongated shell, the length 

 being twice the height, and with the cardinal teeth compressed, acute, and 

 crenated. Having examined a large number of specimens from various 

 parts of New Zealand I have come to the conclusion that neither the shape 

 of the shell nor the form of the teeth can be depended upon for specific 

 characters, indeed hardly two individuals can be found alike ; and from the 

 Eiver Avon, at Christchurch, I have obtained many individuals, living 

 together, which combine in various ways the characters of menziesii, auck- 

 landica, and zelebori, and the animal in all is alike. U. lutulentus is, I 



