698 STUDIES ON AUSTRALIAN M0LLU3CA, xii., 



Ckatis, gen.nov. 



A new genus which, in youth, resembles Philohrya by crenu- 

 lated hinge and prodissoconch cap, but, in maturity, approaches 

 Limarca* bv cuboid form, reticulate sculpture, and massive 

 divaricate cardinal teeth. Type C. progressa, n.sp. Another 

 species is Philohrya ciiboides Yerco. 



Gratis progressa, sp.nov. 

 (Plate Ixxix., figs.21, 22, 23.) 



Shell inequilateral, rather solid, oblong, inflated, becoming less 

 symmetrical with age. Anterior margin straiglit, square to the 

 hinge-line, ventral and posterior margins rounded. Prodisso- 

 conch hat-shaped, with a broad free rim and a central raised 

 boss. Chondrophore broad, central to the prodissoconch. Pri- 

 mary crenulated teeth evanescent, secondary teeth developed as 

 two massive perpendiculars on the anterior side, and three in- 

 clined on the posterior. Medially, the inner margin of the valve 

 is smooth, on either side are half a dozen interlocking tubercles. 

 Height, 4; length, 3-2; depth of single valve, 1*3 mm. 



Hab. —100 fathoms, north-east of Port Macquarie, N.S.W. 

 (self, 1913). 



This species has assumed a secondary dentition, while the 

 primary or crenulated teeth are in process of disappearing. In 

 the characters, by which it recedes from typical Philohrya, it 

 is related to P. cuboides Verco.t That South Australian species 

 differs by a smaller prodissoconch, less height in proportion to 

 length, and a smaller size. 



MoDiOLA PULEX Lamarck. 

 (Plate Ixxix., fig.24.) 



In the previous number of this series (antea, xxxviii., p. 265), 

 the identity of J/, pulex Lamarck, and M. crassus Tenison- 

 Woods, was noted. When that paragraph was w^ritten, it w^as 

 too late to provide an illustration of this unfigured species. The 



* Limarca Tate, type L. angusti/roiis, a Tertiary fossil, Trans. Roy. 

 Soc. S.A., vii., 1885, p. 135, PL viii., f.5. There is a resemblance between 

 this figure and that of Limopsis antillensis Dall, Bull. Mus. Comp. Zool., 

 xii., 1886, PI. viii., f.7. 



t Verco, Trans. Roy. Soc. S.A., xxxi., 1907, p. 223, PI. xxviii., f.5-9. 



