280 NUTTALLINA. 



tallina scabra CPR., MS. and of DALL, Amer. Journ. Conch, vii, p. 

 134 ; Proc. U. S. Nat. Mus. 1878, p. 333.Acanthopleura scabra CPR., 

 Rep, Brit. Asso. 1863, p. 649. STEARNS, Proc. Calif. Acad. iii, p. 

 S4Q.Nuttalliana seabra KEEP, West Coast Shells, p. 108, f. 96 

 (1887.) Not Chiton scaber Reeve. 



This is the form which has generally been called " N. scabra." 

 Reeve's figure is not good, being drawn from a short specimen 

 abnormally shortened by contraction. It should be noted that the 

 shortest specimen in the large suite before me is also one of those 

 collected by Nuttall, who presented a complete set of his Califor- 

 nian shells to the Academy. 



In this species the individual valves are longer than in the follow- 

 ing form, but on account of their deep imbrication the difference is 

 not in most cases noticeable until the shell is dissected. The girdle 

 is much more densely clothed with spinelets. 



The areas of distribution seem to be separated, the true calif ornica 

 extending southward past Monterey Bay, the southern out-post of 

 so many species of the Columbian district, to near S. Simeon, S. 

 Luis Obispo Co. The other species, scabra, has not been noticed 

 north of Sta. Barbara Island, and San Diego on the mainland. 

 There is still a considerable stretch of coast from which we have no 

 record, or at least no record in which the two forms are discrimin- 

 ated. This coast should be searched for intermediate forms. ' 



Dall gives the following notes on the station of this form : This 

 singular species (not yet obtained from Alaska, but which will prob- 

 ably be found there), like some Litorinas, seems habitually to prefer 

 positions where it can at most be reached by the spray in storms, on 

 exposed headlands, where the breeze comes in damp and cool from 

 the sea. The pointed valves overlap each other so much that when 

 the creature is curled up they project from the girdle, giving a pect- 

 inated outline, unusual in Chitons. The valves are almost always 

 eroded, even the prominent mucro is often hollowed out, and the 

 sculpture can rarely be seen except in young specimens. The color 

 is grayish or brownish, with whitish streaks ; the girdle has the 

 aspect of dead brownish-black moss, sometimes with ashy spots at 

 the sutures. 



N. SCABRA Reeve. PI. 54, figs. 21, 22 ; plate 56, figs. 19, 20. 



Shell similar to N. californica, but having the individual valves 

 very much shorter in proportion to their width ; the outer layer of 

 the median valves produced at the sides anteriorly, curving broadly 



