PLACIPHORELLA. 305 



This last seems to be a constant character, and the peculiarity of 

 the tail valve noticed above is also reliable ; but the encroachment 

 of the girdle at the sutures is seen also in M. hindsii ; the lack of an 

 anterior projection or "false beak " is characteristic of many varie- 

 ties of muscosa, such as the elevated var. of lignosa found at Olym- 

 pia, Washington, and the var. acuta Cpr. from southern California. 

 The girdle covering presents a peculiarity not hitherto noticed ; 

 near the base of each of the curled brown hairs, there is a bunch of 

 tiny white thorns or spines. These are also numerous at the edge 

 of the girdle, which is seen slightly rolled upward in fig. 66. 



Dr. Carpenter studied the specimens of " C. ciliatus " in Cuming's 

 collection, and found them to be genuine muscosus ; and therefore 

 Dall in his report on the Chitons of Alaska, as well as other Ameri- 

 can writers, accepted the name ciliata in place of muscosa. Unfor- 

 tunately, the Cumingian specimens are not the true ciliatus of 

 Sowerby, although described and figured as such by Reeve. The 

 original C. ciliatus is identical with the small, green black-mottled 

 form of " wosnessenskii " found at Monterey, etc. 



An excessively rare monstrosity is shown in fig. 67, representing 

 a seven-valved specimen, in which the reduced number is not due to 

 injury or coalescence of valves, each valve being completely normal 

 both outside and within. This figure, and figs. 64, 65, are drawn 

 from Monterey Bay specimens. The sculpture (fig. 68) is stronger 

 and sharper in typical ciliata than in the var. wosnessenskii (fig. 72). 



Var. WOSNESSENSKII Midd. PI. 64, figs. 69-73. 



Shell elongated, the back roundly arched not carinated ; dull 

 colored, varying from light olive or green to drab, generally with 

 blackish patches on each side of the middle, and more or less mot- 

 tled throughout with dusky. Sculpture much fainter than in typical 

 ciliata. Girdle apparently lacking the white spicules described 

 above. 



Sitka (Wosnessenski, figs. 69-71) ; Olympia, Washington (Hemp- 

 hill, figs. 72, 73). 



This seems to be recognizably distinct from the typical ciliata 

 from Monterey, etc. American authors have hitherto given Wos- 

 nessenski an 8 too many. 



Genus XXX. PLACIPHORELLA Carpenter. 



Placiphorella CPR., MS. in Dall, Proc. U. S. Nat. Mus. 1878, p. 

 303, 306. Type P. velata Cpr. 

 20 



