236 Transactions. — Zoology. 



in all specimens. Inside bluish-white, pearly, blotched with 

 yellowish, especially in the umbonal cavity. 



(1.) Lake Waikaremoana (Stat. 37 — Dredged in 15 ft.). — 

 Four specimens of different size, showing all the characters of 

 t hose from Stat. 14. 



In some specimens in my collection, kindly sent to me by 

 Mr. Elsdon Best, and collected in Lake Waikaremoana, the 

 radiate sculpture is distinctly nodulous, sometimes V-shaped, 

 thus approaching D. websteri, Simpson. Typical specimens of 

 aucklandica from creeks near Auckland show the same sculp- 

 ture to a most marked degree, and I consider D. ivebsteri as a 

 D. menziesi in which the nodulous sculpture is developed to the 

 highest degree. 



I have seen, thanks to Mr. E. Best's great kindness, a large 

 number of Diplodon from Lake Waikaremoana, but not one 

 approaching Colenso's type of waikarense, which is a large, thin, 

 yellowish-olive-coloured shell, having more the appearance of an 

 Anodonta. The Waikaremoana specimens are all much smaller, 

 thicker, darker in colour, and less winged. Mr. A. Hamilton, 

 Director of the Colonial Museum, to whom I spoke about it, and 

 who has visited the locality, suggests that Colenso did not get his 

 specimens from Lake Waikaremoana itself, but from some small 

 lake or lagoon in the vicinity. This seems to be correct, as I 

 obtained, again through the unremitting kindness of Mr. E. Best, 

 a number of specimens from a lagoon near Ruatoki, Tuhoe- 

 land, and these are typical waikarense, Colenso ; one of them 

 showing the same outline and the same dimensions as the cotype 

 in the Canterbury Museum. 



An error in Colenso's diagnosis of Unio waikarense (Trans. 

 N.Z. Inst., xiv., 169) wants correcting. He says, "Posterior 

 slope keeled." This, however, is not correct : the shell is not keeled. 

 How misleading such an incorrect statement is may be guessed 

 Erom Simpson's remark on the species in his "Synopsis of the 

 Naiades," p. 890 (footnote) : " Suter thinks this is a variety of 



iziesi, but Colenso states that the posterior slope is keeled. 

 If this is so it must be quite different from the species." Then- 

 is also an error in the quotation in Simpson's work, as he gives 

 t he year 1841 as t lie date of the publication of the Tasman. Journ. 

 Nat. Sci. vol. h., whereas it is 1845. Colenso says thai he dis- 

 covered the shell iii 1841, but his description was published four 

 years later. 



1 have compared typical specimens of waikarense with many 

 specimens of menziesi Erom aboul twenty differenl localities. 

 and I am unable to separate the two. In all essential characters 

 the two agree, and there remains nothing but to make Colenso's 

 species a Bynonym of D. menziesi, Gray. 



