ISCHNOCHITON. 121 



I. RADIANS Carpenter, n. sp. Unfigured. 



Shell rather large, wide, elevated, the jugum acute ; olivaceous, 

 elegantly radially streaked with brown. Interior blue-green with 

 two brown rays. Valves delicate, flat, produced in the sinus in 

 front ; mucro in front of the middle, scarcely elevated ; entire sur- 

 face quincuncially granulated ; lateral areas scarcely denned, and 

 with the end valves obsoletely sublirulate. Interior : posterior 

 valve having 9-10, central valves 1, anterior valve 10-11 slits; 

 teeth acute; eaves small; sinus wide, short, scarcely laminate. 

 Girdle regularly covered with solid, coarsely striated, moderate sized 

 scales. Length 21, breadth 15 mill.; divergence 110. (Qor.) 



Monterey, California. 



The internal color-rays are seen in all the dead valves; the 

 external painting resembles Mopalia vespertina. The sculpture is 

 on the plan of/, interstinctus. One central valve of one specimen, 

 on one side only, had a second slit. (Qpr.) 



8. Group of I. scabricostatus. 

 I. SCABRICOSTATUS Carpenter. Unfigured. 



Shell small, orange colored, elevated ; valves gothic arched, jugum 

 acute. Entire surface very closely granulated ; lateral areas well 

 denned, with 3 subobsolete, radiating series of large granules ; 

 beaks scarcely apparent ; umbonal margin slightly turned inward, 

 and having dark spots giving a false appearance of teeth. Central 

 areas having separated longitudinal series of narrow, subobsolete 

 riblets, furnished with large granules. End valves having similar 

 radiating granulous riblets. Umbo of posterior valve scarcely cen- 

 tral, little projecting. Interior: sutural plates separated by a large 

 flat sinus ; insertion plates subobtuse, the end valves having 10-12, 

 central valves 1 slit; eaves moderate, sui)conspicuous. Girdle 

 wide, closely clothed with imbricating, elongated, transversely 

 striated scales. Length 7*, breadth 41 mill, ; divergence 100. 



(Qpr.) 



Catalwa Island, California, in 10-20 fms. 



Lepidopleurm scabrieostatus CPR., Rep. Brit. Asso. Adv. Sci. 

 1863, p. 649 ; Proc. Cal. Acad. N. S. ii, p. 212. Ischnochiton seabri- 

 costatus CPR., MS. 



The sinus has a thin, smooth lamina separated by a slit on each 

 side from the sutural laminae. It is a small, arched orange species, 

 with rows of prominent granules over a shagreened surface. ( Cpr.) 



