'.) ISCHNOCHITON. 



acute ; sinus very broad, flat ; eaves large, scarcely spongy. Girdle 

 thin, irregularly imbricated with very small, very close, solid, sub- 

 elevated, conspicuously sulcated scales. Australia. Five speci- 

 mens, P>. M.. the tablet including two specimens of longicymba and 

 one of Heterozona cariosa f. 



In the first specimen the radiating sculpture is almost lost in the 

 i:ranulc< in the side areas. The painting is sometimes with delicate 

 broken lines of brown longitudinally. Sometimes one jugular 

 patch more or less broken into streaks, side areas rarely if ever 

 painted, but often tinged with bluish green. The specimen opened 

 B. M. has 2 central teeth on posterior valve changed into an irreg- 

 ular series of pectinations evidently consequent on an injury. 



I. INQUINATUS Reeve. PL 18, figs. 49, 50 (enlarged). 



Shell oblong-ovate ; terminal valves and lateral areas concen- 

 trically, somewhat obscurely ribbed, finely radiately grooved; cen- 

 tral areas longitudinally finely ridged. Ligament horny, arena- 

 ceous. Whitish, stained with a light brown spot along the summit 

 of each valve. (Rve.} 



Tasmania. 



C. inquinatus RVE., Conch. Icon. t. 23, f. 154, May, 1847. Isch- 

 nochiton inquinatus CPU., MS. 



The shell is sometimes partially stained throughout with the 

 faint brown color which appears on the umbonal summit. (Rve.) 



Compare /. divergens Rve. 



I. DIVERGENS Reeve. PI. 22, figs. 74-77. 



Shell oblong, moderately elevated, varying from obsoletely to 

 distinctly angled at the dorsal line. Lateral areas raised and 

 rugose. Color very variable, but usually a light green tint, spotted 

 with dark olive-brown, or cream-white, variegated w r ith olive, olive- 

 brown or dull scarlet. 



The raised lateral areas are sculptured with a varying number of bi- 

 furcating or irregular riblets, the surface between them being granular. 

 Central areas sculptured in the middle with very fine subgranose strice 

 diverging forward /\-likefrom the dorsal ridge ; pleura or sides of the 

 << ntral areas having stronger longitudinal rugce at the sides and on 

 the diagonal slope ; a region of fine zigzag striation sometimes inter- 

 vcninir between the side corrugation and the A'like >t nation of the 

 jugal tract. End valves sculptured like the lateral areas. Umbo 



