13 



flat pustules, widely spaced, and the rows widely separated 

 from one another. All pustules are placed on the diagonal, 

 and the rows themselves become more and more diagonal as 

 the margin of the shell is approached. Slit 11 modified into a 

 deep groove, with raised edges on the upper side of the 

 articulamentum . 



Measurements. — 3 mm. longitudinally, 3*75 mm. laterally. 



Habitat. — A number of valves dredged 7 miles east of 

 Cape Pillar, North-west Tasmania, in 100 fms. ; one valve, 

 about the same depth off Schouten Island ; one valve, coloured 

 red, off Port Arthur, South-east Tasmania, in 60 fms. 



Specimen No. 2. Co-type. 



This median valve was likewise dredged in the same depth 

 east of Cape Pillar. While corresponding, in the main, with 

 the preceding valve, it differs in that the dorsal area is uni- 

 formly covered with short, deep, wedge-shaped, longitudinal 

 grooves. Also the fold separating the pleural from the lateral 

 area is very strongly raised, and the pustules in the rows, 

 where they pass over this fold, are larger and broader than 

 anywhere else, for a width of two pustules. If these pustules 

 had not been so widely spaced one would have described the 

 valve as possessing a wide diagonal rib composed of two rows 

 of pustules. In method of sculpture and shape of the pustules 

 the two valves described are otherwise identical. 



In conclusion. — The type is being presented to the Tas- 

 manian Museum and is figured from a drawing. The co-type 

 is figured from a photograph taken by the writer and remains 

 in my own collection. In a paper on Polyplacophora of Tas- 

 mania, by W. L. May and Dr. Torr (Proc. Roy. Soc. Tas., 

 1912, p. 35), a note is made that the valves described above 

 were wrongly identified by Hedley and May (Rec. Austr. 

 Mus., vol. vii.. No. W, 1908) as Acanthochiton crocodilus, 

 Torr and Ashby. 



Acanthochiton shirleyi, n. sp. 

 Specimen No. 1. Type. 



General appearance. — Broad, girdle wide, densely and 

 coarsely spiculose, shell flat and low, the spicules of the girdle 

 standing up above the shell. 



Colour. — Some valves are darkhorri-colour, others are 

 creamy-white; the dorsal area is creamy-white in some valves. 



Anterior valve. — ^I cannot notice any rays or undula- 

 tions. The sculpture on this valve is largely eroded, but it is 

 evidently well covered with circular pustules. Insertion plate 

 long,- slits 5, notch very short but continued on upper side in 



