Suter. — On New Zealand Mollusca. 235 



a subspecies, but I had to give it up, as I had numerous specimens 

 before me which could be either assigned to menziesi or to auck- 

 landica. There is no doubt that when the extreme forms only 

 are compared one would feel inclined to take them for distinct 

 species, but so it is with many other species, as for instance with 

 Helcioniscus tramosericus. However, it is convenient to refer to 

 aucMandica as a form of menziesi which is but little winged, and 

 having the dorsal and ventral margins subparallel. 



Unio waikarense will be dealt with further on when describ 

 ing the mussels from Lake Waikaremoana. 



(1.) Lake Taupo (Stat. 9 — From dredgings up to 100 ft.). — 

 There are eight specimens, representing quite young to half- 

 grown forms, only one being highly winged. All are distinctly 



radiately striate, and some of the 

 youngest specimens show the typi- 

 cal beak-sculpture beautifully. It 

 is represented by the accompany- 

 7 [ "^yjm\ ing diagram (fig. 1). One of the 



larger specimens is very distinctly 



sculptured with elongate nodules on 



the lower half down to the ventral 



margin in the region below the 



beaks. The interior and hinge are 



the same as in specimens of subspecies hochstetteri, to be described 



further on. The largest specimen measures — Length, 42 mm. ; 



height, 28 mm. ; diam., 13 mm. 



(2.) Lake Taupo (Stat. 9f — From dredgings up to 100 ft.). — 

 The eight specimens have the same appearance as those of the 

 last station ; all of them have the outline of aucMandica, are 

 finely radiately striate, and one clean olive-coloured specimen 

 also shows nodulous ornamentation. Five quite young speci- 

 mens have the beaks already so much eroded that no trace of 

 the beak-sculpture is left. A few specimens have a light ferru- 

 gineous coating. The largest specimen shows — Length, 43 mm. ; 

 height, 28 mm. ; diam., 13 mm. 



(3.) Lake Waikaremoana (Stat. 14 — Dredged in 50ft.). — 

 Compared with the type of Unio waikarense, Colenso, said to 

 have been obtained in this lake, the four specimens collected at 

 this station are much smaller, very little winged posteriorly, the 

 dorsal margin subparallel to the ventral, darker in colour, and 

 more solid ; they are not concentrically sulcated, but only 

 striated, and the marks of rest are much less distinct. All of 

 them are finely radiately striated, a character always to be found 

 in menziesi. The pseudocardinals are typical, the upper lateral 

 tooth in the left valve is much lower than the other, and crenate 



