20 



similar specimen with pitting confined to the same valve; all 

 these were taken in this State. In going through a score of 

 specimens in my own collection from New South Wales, 

 Tasmania, South Australia, Western Australia, and New 

 Zealand, with the exception of one specimen 25 mm. long 

 from Sydney, which is pitted in the seventh valve, all are 

 typical unpitted shells. Mr. W^, L. May has sent me for 

 examination three large and handsome specimens from Watson 

 Bay^ New South Wales, all of which show similar pitting on 

 the seventh and eighth valves, and the largest one, which is 

 over 40 mm. long, has incipient pitting in the sixth valve 

 as well. In this specimen I counted 12 pits in the seventh 

 valve. These pits commence high on the ridge in the juvenile 

 shell. The pits are deep and only a little longer than broad, 

 in fact very similar to the pits near the ridge of Rhyssoplax 

 oruktos, Maughan, but there the likeness ends — they are not 

 as regular in shape nor developed to the same length as in 

 that species. Again, the character of the pitting is quite 

 different from C. rufus, Ashby. I have compared it with 

 the type and with the juvenile form from the Bracebridge 

 Wilson collection; the grooving of rufus can hardly be termed 

 pitting, but is really longitudinal grooving, and is present to 

 an equal extent in all the valves except the first. 



In conclusion. — The existence of these pits and their 

 occurrence consistently on the seventh valve, and in the case 

 of the Watson Bay specimens on the eighth valve as well, 

 suggests a definite tendency to vary in this direction. At first 

 I thought of suggesting that deep-water specimens may have 

 a greater tendency to develop this form of sculpture, and that 

 C. rufus (which is only known from dredge specimens) may 

 have been derived from such a pitted race of G. platessa. 

 On more careful examination, however, I do not feel justified 

 in advancing such a. hypo thesis. It will be well worth while 

 for collectors to keep their eyes open for this variant, which 

 may well be known as Callochiton platessa, var. fossa, Ashby. 



Sypharochiton pellis-serpentis, Quoy and Gaimard, 1835. 



(Chiton pellis-serpentis, Quoy and G. Voy, Astrol., ii., 381, 

 pi. 74, f. 17-22; Man. Conch. (1), xiv., 173, pi. 37, f. 14-17; Proc. 

 Mai. Soc, ii., 195, c. Squamosus^ L. Wissel, Zool. Jahrb., xx., 

 619, not of Linne (Anatomy); Tate land Mav, Proc. Linn. Soc. 

 N.S. Wales, 1901, pt. 3, pp.' 412-415; May and Torr, P. and Proc. 

 Roy. Soc. Tas., 1912, pp. 38 and 39. Type, Mus. Hist., Paris.) 



Sypharochiton sinclairi, Gray, 1843. 



(Dief., N. Z'd, ii., 263; Man. Conch. (1), xiv., 174, .pi. 36, 

 f. 1-3; Proc. Mai. Soc. ii., 196; Wissel, Zool. Jahrb., xx., 627, 

 pi. 23, f. 38-44, pi. 24, f. 45-48 (Anatorav), Type, Brit. Mus.) 



