300 RKCORDS OV THE AUSTRALIAN MUSEUM. 



MoDIOLA LINEA, sp. IIOV. 



(Plate Ivi., figs. 23, 24, 25). 



Shell small, thin sub-cvlindrical, smooth and glossy, anteriorly 

 slightly produced and angled, posteriori}- rounded, dorsal and 

 ventral margins parallel. Umbo low, a little incurved, at a fifth 

 of the total length. Colour white, with a few small, scattered, 

 brown dashes. Sculpture regular, concentric growth stria?, which 

 posteriorly are traversed by a few faint impressed rays. Perio- 

 stracum tliin, polished. Hinge edentulous. Length, 5*75 ; 

 height, 2-5 ; depth of single valve, 0-9 mm. 



In our fauna the novelty is nearest related to Mudiola arhores- 

 cens, Chemnitz,-^ which is far larger, and even in its young 

 stages, of quite difi:erent contour. 



Crassatellites discus, sp. nov. 



(Plate hi., figs. 26, 27). 



Shell small, thin, sub-quadrate, lenticular, inequilateral, the 

 posterior side being twice the length of the anterior ; dorsal and 

 posterior margins straight, ventral slightly rounded, anterior pro- 

 duced. Colour ; buff or vinous, with a few broken radial streaks. 

 Sculpture : umbo and neighbouring area smooth, followed by about 

 a dozen sharp, even, elevated, concentric folds, parted by equal 

 interspaces. Over these run a microscopic sculpture of extremely 

 fine concentric scratches. Lunule and dorsal area elongate and 

 narrow. Inner margin of valve smooth and bevelled. Height, 6 ; 

 length, 7 ; depth of single valve, 1-7 mm. 



A group of small, short CrassafeU if e.s horn East Australia much 

 resemble one another. Single specimens seen separately are diffi- 

 cult to distinguish, but a series of each demonstrates that slight 

 though the differences be, they are constant. C. fvlvidd, 

 Angas,-' is larger; C. janus, Hedley,-" is smaller than C. discus; 

 besides colour differences, both are more infiated, stronger ribbed, 

 and the anterior and posterior margins meet at a more acute 

 angle. The former has, the latter has not, small denticules on the 

 inner margin. ( '. secnri/orme, Hedley,^' is longer in proportion 

 to height, the nearly straight dorsal margin, almost at right angles 

 with the anterior margin, distinguish it from ('. discus. 



••21 Chemnitz— Coia-h. Cab., xi., 1795, p. 251, pi. 19S, f. L'016-17. 



« Angas— Proc. Zool. Soc, 1871, p. 20, pi. i., f. 32. 



2« Hedle^ — Proc. Linn. Soc. X. S. Wales, xxxi., 190f^, pi. xxxviii, f. z9-30. 



27 Hedlev-Mem. Austr. Mu3., iv., 5, 1902, p. 312, f. 53. 



