M i i \ i i 281 



forward and literally Upon thfl sutural plat<--; flu- medi;m i 

 and sulci inoiv or !. 'I ail valve -li'Ti.r, with less pos- 



terior macro, Oolor of yalvei li.irht vaiir-at.'d. 



Girdle rusty brown or alternately blacki-h and white ; 

 rather spar-ely scattered white sj)ik--lik<- -j.i 

 one or two at each suture. PI. ">J, fig. 21). length :>!, breadth 

 L3 mill. 



Santa Barbara Is. ami XHH I>i/()to between Soo/mn 



<Ul<I rtd. tie -1 /'/V/'f*S, Jjnir,,- ( 'il/ifi>rn i'l . 



Chiton scaber h'u.vi:. Conch. Icon., t. 17, f. 106 (March, 1847). 

 Acanthopleura fluxa CPR., Suppl. Rep. Brit. Asso. 1863, p. 649; 

 Proc. Cal. Acad. iii, { >. 211, (1865.) 



This species has hitherto been confused with the preceding by 

 most collectors. Carpenter, however, distinguished it, and gave the 

 name fliu-n. Although the individual valves are much shorter in 

 this species than in N. californica, they overlap much less, so that 

 the total length of the animal is about the same in the two species. 

 The elevation is about equal also, but in californica the girdle is 

 generally wider at the sides, especially in old specimens. In size, 

 individuals of the northern species considerably exceed any of the 

 southern I have seen, although the majority of specimens do not 



differ much. 







N. ALTERNATA Sowerbj. PL 54, figs. 25, 26, 27. 



Shell elongated, subdepressed, very minutely granulated ; lightly 

 keeled by a central rib ; lateral areas separated by a lateral rib. 

 Anterior valve radiately ribbed ; posterior valve small. 



Girdle furnished with minute spines, alternately banded black 

 and white. Length 15, breadth 8 mill. 



Narrow, rather flat, minutely granulated; the first valve radiated 

 with slightly raised ribs, the intermediate have each three faint 

 ribs, one dorsal, the other two lateral ; the la>t U very small, with 

 a nearly terminal apex. The margin is covered with very minute 

 spines, in alternate patches of black and white; general color, dark 

 olive-green. (Sowb.) 



(Mus. ( 'inning). 



Chiton alternatus Sown., Mair. of Nat. Hist., IMn, p. 288 ; Conch. 

 Illustr., f. 141. 



