Ill/in III K.N. 



posterior sinus, however, is unlike tin- former group, in which the 



tail valve approaches the head valve in form ; and tin- arrant ni'-nt 

 of the eyes is (he same as in Lorir.i, vvliidi has a degenerate tail 

 in<ertion-plate. At the same time, it must be granted tli at tin- differ- 

 ences between Si'hi:in'hifn and Lnrim a re greater than between most 

 genera of the same family; for in Schizochiton the slits of the head- 

 valve are inimerieall y related to the external ribs; the latter bear 

 and the tail valve has a well developed slit and pectinated 

 insertion-plate. 



S. iNviM's Sowerby. PL 51, figs. 1-8. 



Shell much elongated, narrow, the valves elevated, somewhat car- 

 inated ; surface lusterless, grayish, obscurely mottled with olive and 

 purplish. 



Median valves elongated, beaked, the lateral areas small, slightly 

 raised. Entire surface sculptured with flattened longitudinal riblets r 

 as wide as their interstices, converging toward the dorsal ridge and 

 somen'hat irregular or wavy on the lateral areas; each riblet where it 

 passes over the diagonal, enlarged for the insertion of an eye. Ante- 

 rior valve (figs. 2, 4) having 6 (sometimes 7 or 8) radiating curved 

 ribs, each bearing a series of eyes, the intervals sculptured with close 

 v-shaped riblets. Posterior valve (figs. 6, 7, 8) having the mucro 

 posterior, the latero-posterior areas tricostate, otherwise sculptured 

 like 'the median valves ; posteriorly it has a wide, deep fissure, extend- 

 ing up to the mucro (fig. 8.) 



Interior whitish, stained with purple-brown in the middle of each 

 valve. Sutural plates well developed. Sinus V-shaped. Anterior 

 valve having 6, central valves 1 or 2 slits; posterior valve, on each 

 side of the posterior fissure, 3 slits ; teeth thin, distinctly creii- 

 ulated outside. 



Girdle broad, alternately buff and dark colored, the light stripes 

 wider, and as usual, sutural ; rather thinly but in places densely 

 clothed with minute, cylindrical, shelly spinules, part brown, part 

 white. Length 50, breadth 18 mill. 



Zebu, (Cuming), and Samboangan, (Challenger), Philip/tines; 

 Raines Island, Torres Straits (Ince) ; Clairmout <IH<! Bird Is., 

 N. E. Australia (Coppinger) ; Sulu Sea (Capt. Chimmo.) 



Chiton incisus SOWB., P. Z. S. 1841, p. 61. REEVE, Conch. Icon, 

 f. 43.Sehizochiton liu-i^u* GKAY, P. Z. S. 1847, p. 169. SHUTTL., 

 Bern. Mittheil. 1853, p. 68. H. & A. AD., Gen. Rec. Moll, i, p. 477, 



