50 CRYPTOCHITON. 



Occasional individuals are variegated with gray-white or pinkish 

 patches, the specimen figured being one so marked, received from 

 Mr. Newcomb, of the Provincial Museum, Victoria, British Col- 

 umbia. The valves of this specimen are of a beautiful pink color 

 inside. The largest specimen I have seen is in the collection of Mr. 

 John Ford ; if straightened out it would measure over 8? inches in 

 length. Some other specimens before me are yellow on the back, 

 but a minute examination shows that they have lost the red bunches 

 of minute bristles. 



The number of slits, and even their presence varies greatly. 

 Valves ii and vii are usually provided with slits, but the other inter- 

 mediate valves lack them. The posterior valve generally has slits, 

 even in individuals quite adult ; but sometimes they are obsolete, 

 being filled in by an excessive thickening of the posterior edge of the 

 valve. The mucro of each valve is in most cases quite inconspicuous, 

 but on some valves of occasional specimens it is raised in a minute 

 point, or marked by a puncture ; in either case being still covered 

 by the general integument. 



It is by no means certain whether any true varieties or geographic 

 races exist; but the following may be accepted provisionally. 



Var. VIOLACEUS Nordmanu. PI. 6, figs. 1-5. (Living spec- 

 imen.) 



Beautiful violet colored when living, fading in alcohol to a dark 

 brick-red, with large rounded light gray spots. A dried individual 

 is dirty gray-reddish above. Largest specimen measures along the 

 convex back 152 mill. ; the smaller individual figured measures 90 

 by 63 mill. 



Sachalin I. 



The colors of the living animal are thus described by Arthur 

 Nordmann : Cryptochiton stelleri varies much in its coloration ; in 

 some examples the ground-color of the convex back is clear brownish- 

 red ; in others yellowish-red ; in still others, but rarer, beautiful 

 dark violet with lighter streaks undulatingly passing outward from 

 the median line, and indicating the number of valves. * 

 The under side is dirty yellowish, the foot sometimes butter-yellow, 

 the long, narrow girdle of gills (consisting of 140-150 leaflets) being 

 reddish. 



Var. APICALIS Pilsbry. 



All characters as in C. stelleri except that the apices of the valves 

 are distinctly projecting as small circular elevations; substance of 



