241 



disarticulated specimen must be considered the type. The following is an abstract 

 of his description, which I believe has not heretofore been published in English : — 



"Anterior valve, partly eroded, confusedly granulose ; valve 2, fairly narrow- 

 dorsal area, granules in lateral portion gradually merging into longitudinal 

 ridges ; in valve 3 he refers to distinct longitudinal folds in the lateral parts ; 

 valves 5 and 6 are the smallest, and the seventh distinctly larger. The posterior 

 valve is a little pointed anteriorly and rounded posteriorly ; the mucro is a little 

 in front of the posterior margin; the smooth dorsal area is narrow, and the 

 folds of the remaining part radial from the apex." 



Notes on the specimen collected by the writer at Yallingup, Western Aus- 

 tralia, in October, 1920 : — 



The specimen is 12 mm. in length, about one-quarter that of Thiele's 

 larger shell, and therefore a little over one-sixteenth of the bulk of that specimen. 

 In the Yallingup shell all the valves are touching, but this is to be expected ; the 

 valves of most species that are spaced in the adult are at this stage imbricating. 

 Thiele's description, taken with the figures, well fits my specimen ; but to this 

 I would add that the granules in the anterior valve are in somewhat confused, 

 intercalated rows, the grains are elongated like tear-drops, and placed diagon- 

 ally in the rows. The sculpture of the other valves consists of longitudinal 

 rows of semitransparent, white granules, commencing small near the dorsal area 

 but increasing in size and elongation anteriorly and laterally. In no case can 

 the outer row be said to coalesce into a rib, as stated by Thiele, but not shown 

 in his figures ; still the outermost granules are so crowded that one may conclude 

 that, in older shells, this feature will come into being. The grains, although 

 much raised, are not as rounded and bead-like as in the Crytoplax from Sydney. 

 The most distinctive character of the shell is the arrangement and shape of the 

 spicules. Thiele's figs. 23 and 24 (I.e.) well depict 95 per cent, of the spicules, 

 the striae are as drawn and easily seen. Most of the spicules of the Yallingup 

 specimen are shaped like his longer figure, but in stoutness half-way between 

 his two figs. 23 and 24. I cannot notice the slight latteral compression noted 

 by Thiele. The spicules (his fig. 26) are only met with in the bunches at the 

 sutures. It should be noted that his fig. 24 is drawn upside down. In the 

 Yallingup specimen the spicules are white and widely spaced, a feature that is 

 not mentioned by Thiele, but is certainly a striking and distinctive character. 

 The ground colour of my shell is horn colour, and no mottling can be seen on 

 the girdle, but this character is quite unimportant, and may have existed only 

 on Thiele's large specimen. 



In conclusion. — The widely-spaced, short, stout, slightly-curved, and bluntly- 

 pointed spicules separate this species at once from any of the forms with which 

 we are familiar in Eastern Australia. 



Cryptoplax oculatus, Quoy and Gaimard, 1834. 



f Chiton oculatus, Q. and G., Voy. Astrol., Zool., iii., p. 410, pi. 72 or 73, figs. 37, 38, 1834 ; 

 Chitonellus fasciatus, Q. and G. of Reeve; C. montanoi, Rochebrune; Ashby, Trans. Rov. 

 See. S. Austr., vol. xlvi., 1922.) 



While this species is very close to C. larvaeformis, Burrows, reference 

 to my paper (I.e.) will show that in this latter species only the two first valves are 

 circular, whereas my specimen of C. oculatus, from Island Sula. has the three first 

 valves broad and circular. On comparison with specimens of the former from 

 Tonga (given me by Major Dupuis) I note that the spicules of the Sula shell are 

 longer and quite distinct, also, as noticed by Dr. Pilsbry, the three anterior valves 

 of C. oculatus are surrounded by a broad margin of longish, black spicules, with 

 another outer ring of white; this feature is quite absent from the Tonga shells. 



