AMICULA. 47 



? Chiton pallasii MIDD., see below. 



It would be a distinct advantage to science if the attempt to 

 identify Chiton amiculatus could be given up. The figures of Pallas 

 indicate a species externally very similar to A. vestita in the dry 

 condition, except that the exposed portion of the valves, and as far 

 as known their entire structure, accords completely with that of A. 

 2)allasii Midd. There is not much doubt in my mind that the A. 

 pallasii really is the same as the original amiculatus, notwith- 

 standing its apparently thicker and more hairy integument. 



Carpenter identified as amiculatus a form collected by Dr. New- 

 comb on the Farallones Is., off San Francisco Bay. He describes it 

 as follows : 



" Amicula amiculata (? Pallas). PI. 5, figs. 12, (13, 14 ?). 



Shell externally resembling a young C. stelleri, but the apices of 

 the valves are present and rounded ; inside the insertion plate of the 

 posterior valve is Mopaloid, having one slit on each side, like the 

 intermediate valves; the caudal sinus is wide and deep. The ante- 

 rior valve has . . . . ? slits. The anterior sutural-laminse of each 

 valve are moderately connected across the broad sinus ; the posterior 

 sutural-laminse are larger, regularly arcuate, hardly sinuated out- 

 wardly, having a broad deep sinus behind, flat behind the apex 

 and hardly laminated. Slits grooved up to the apices. Girdle 

 coriaceous, smoothish, with two series of larger pores at sutures and 

 margin, and series of smaller pores placed between the valves and 

 irregularly, sparsely scattered over the girdle ; setae of the pores few, 

 long, hardly spicular." 



"The shell here described must have been about 3 inches long 

 when living, and rather more than half the breadth. It accords 

 sufficiently nearly with the very brief description of Ch. vestitus 

 Brod. & Sby. in the Zoological Journal, but not with the figure of the 

 specimen there described in Conchological Illustrations. Moreover 

 the gills of Ch. vestitus are median, of this (as far as I can judge from 

 the dried remains) ambient, which is the character of Ch. amiculatus, 

 teste Midd. It was sent by Dr. Newcomb to Dr. Gould as the young 

 of Ch. amiculata Sby. (==stelleri') ; from which it differs (1) in the 

 round mucro, which represents in fact the jugular, central and side 

 areas squeezed up into a knob which alone projects at the posterior 

 part of each of the 7 anterior, and the middle of the hind valve ; (2) 

 in the posterior sutural laminae being a curved continuation behind 

 of the side laminae not separated by waves at the sides, but separated 



