272 Transactions. — Zoology. 



is somewhat higher in proportion to the length of the aperture 

 than in the type specimen figured. 

 Type in the British Museum (?). 



Isidora hochstetteri, Dunker (1862), sp. 



Physa hochstetteri, Dunker, Malac. Blatter, vol. ix. (1862), p. 150. 

 Physa guyonensis, T.- Woods, P.L.S. N.S.W., vol. iii. (1879), 

 p. 138, pi. xiii., fig. 4. Physa guyonensis, Hutton, Man. 

 N.Z. Moll., p. 30. Physa guyonensis et hochstetteri, Hutton, 

 P.L.S. N.S.W., vol. vii., p. 67. Bulinus guyonensis et hoch- 

 stetteri, Hedley and Suter, P.L.S. N.S.W. (2), vol. vii., pp. 627, 

 628. Bullinus guyonensis et hochstetteri, Suter, Journ. de 

 Conch., vol. xii.,' pp. 232, 233. 



The diagnosis of guyonensis is in Hutton's Manual. The 

 accompanying fig. 3 is drawn from a tracing 

 of the figure given by Tenison- Woods. 

 Captain Hutton mentions (Manual) that Dr. 

 Dohrn determined specimens from the same 

 locality (Lake Guyon) as P. hochstetteri, Dkr. 

 The diagnosis agrees in the main points with 

 that of T.- Woods, and Dunker particularly 

 mentions the deep suture and the amplitude of 

 the body-whorl. I do not hesitate to accept 

 the determination of the distinguished con- 

 Fig. 3. chologist, Dr. Dohrn. The dimensions of 

 P. hochstetteri are— Height, 17 mm. ; breadth, 

 9 mm. For P. guyonensis the dimensions given by T. -Woods 

 are — Height of shell, 15 mm. ; breadth, 7| mm. : aperture — 

 height, 9 mm. ; breadth, 5 mm. I have not seen specimens 

 from Lake Guyon, but I have shells from Lake Nga-tu, Kai- 

 taia, which I consider to belong to this species, although they 

 are somewhat shorter and more ventricose than the type ; 

 otherwise they agree with the diagnosis. Especially the deep 

 suture is characteristic, no other of our species showing this 

 character in such a marked degree. All my examples are 

 " dead shells " of a light-brown colour. 



For /. guyonensis the rationis are — i. = 1:2; ii. = 1 : 1*8 ; 

 iii. = 1:L7. For hochstetteri — i. = 1 : 1*9. I measured four of 

 my specimens. The length of the shell varies from 13J-14S mm., 

 the breadth from 8-9 mm. Aperture — length, 8-9 mm. ; breadth, 

 4-5 mm. The mean proportions are — i. = 1:1-6; ii. = 1 : 1*9 ; 

 iii. = 1 : 1-6. 



Hab. The only localities known to me are Lake Guyon, 

 Nelson, and Lake Nga-tu, in the high north. 

 Type in the K.K. Hofmuseum, Vienna (?). 



