Ieedale. — Neiv Zealand Marine Molluscs. 375 



Plaxiphora ovata (Hutton). 



Plaxiphora ovata (Hutton), Suter, Proc. Mai. Soc, vol. ii, p. 191, 

 1897. 



References are given in this paper, where Suter writes, " This 

 handsome but rare mollusc is found mostly in roots of D'JJr- 

 vittea." I have never yet found it on any other station, and, 

 searching for specimens at Sandfly Bay, Otago Peninsula, my 

 friend Mr. W. R. Brook Oliver obtained a lovely specimen 

 with six valves only. 



In the succeeding note, written previously to this find, the 

 rarity of this find is shown. As this is the first occurrence in 

 New Zealand of such an abnormal specimen, I am giving an 

 illustration of it (Plate XXXI, fig. 1). In this specimen it will 

 be noticed that the last valve is of unusual size for this species, 

 the shape of the last valve in normal specimens being one 

 of the chief characters of the subgenus Fremblya, which in- 

 cludes only one other species, P. egregia, H. Adams, of New 

 South Wales. 



Chiton pellis-serpentis, Quoy and Gaimard. 



Chiton pellis-serpentis, Q. and G., Suter, Proc. Mai. Soc, vol. ii, 

 p. 195, 1897. 



In the paper quoted, Suter gives full references. I have to 

 record the occurrence of a specimen of this species having five 

 valves only, and herewith give an illustration from a photograph 

 (Plate XXXI, fig. 2). This specimen is, as far as I can trace, 

 unique. 



Pilsbry wrote (Man. Conch., vol. xiv, p. xiii, 1894), " The 

 occurrence of 6- and 7-valved Chitons has been noted as early as 

 the time of Linnaeus. It is likely that the 6-valved were artificial 

 fabrications, although a certain number may perhaps be traced 

 to incorrect drawings." Since the publication of Pilsbry's mono- 

 graph increased interest in the collecting of Chitons has caused 

 undoubted instances to be put on record. 



In the Proc. Mai. Soc, vol. ii, p. 154, 1897, Bednall records 

 the occurrence of a 6-valved specimen of Plaxiphora conspersa 

 (Ad. and Ang.). Sykes, in his presidential address on "Vari- 

 ation in Recent Mollusca " (Proc. Mai. Soc, vol. vi, p. 268, 

 1905), mentioned that 6-valved specimens of Trachydermon 

 ruber, Linne, and Ischnochiton conspicuus, Cpr., had recently 

 been noted elsewhere, and that he himself had met with a 

 3-valved specimen of Ischnochiton contractus, Reeve, which is 

 preserved in the British Museum. 



