312 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



hand planato; lam. post, super-suturalibus minoribus, longis, a siiiibus 

 inargiiialibus conspicue separatis ; sinn postico altisshno, irregulariter 

 gothico, lam. junctis ; valvis omnibus mueronatis, mucrone seu umbili- 

 coideo seu punctato seu pustulo'so ; zona omnino fasciculis minutis 

 spicularum minimarum irregulariter conferte instruct;!. (Cpr.) Lou. 

 200, Lat. 75 mm. Div. 13(P. 



Hab. — Japan Sea ; Sakalin Id. ; Kuril Ids. ; Kamchatka (southern 

 extreme) ; the Aleutian Islands and the whole coast southward to 

 Monterey and the Santa Barbara Islands, California. Usually found 

 just below tide-marks, and often cast up on the beach in great numbers 

 by severe gales. Collected abundantly at Unalashka and Sitka, also at 

 Monterey ; Dall ! 



This the largest and in many other respects the most remarkable of 

 all Chitons is readily recognized by its wholly covered valves, no indi- 

 cation of which is evident, even under the skin, in fresh examples. It is 

 (covered with cells, each holding a fascicle of small spines, which, when 

 dry, have an urticating effect upon the skin of those who may handle 

 them. The foot and softer parts are used as food by the Aleuts and 

 Indians ; they are eaten in the raw state. The back is of a fine ferru- 

 ginous red when fresh ; dried specimens are usually more or less dis- 

 torted and mauled ; one of those figured by Reeve appears to have been 

 partly rotten. 



There is a good deal of variation in the size and relative proportions 

 of the valves in different individuals, and the fissures are sometimes 

 partly abortive or abnormally multiplied. 



The soft parts of this species have formed the subject of an extensive, 

 monograph by Dr. Middendorf in his first pari of the Beitr. Mai. Ros- 

 sica. To that work the student is referred for details. 



Genus KATIIKRIN A Gray. 

 Ealhcrina Gray, P. Z. S. 1847, p. Go. Typo K. iunicata Wood. 



Lorica parva; zona larvis, in suturas valde expansa; laminae valde 

 anticc project®, v. post. s»pe lobatae; sinus altissimus, spongiosus; 

 branchiae ambientes. 



This is an aberrant genus. In the smallness of the exposed portion 

 and smoothness of the girdle it resembles Phacellopleura ; in the extreme 

 anterior projection of the plates, and in the deep spongy sinus, it is most 

 like NuttaUina, of which it might be regarded as an exaggeration with 

 a smooth girdle ; but the tail-plate has most affinity with the Mopaloidea. 

 Specimens maybe found with many lobes like Phacclloplcura ; but on 

 comparison of many individuals it will be found that the normal ar- 

 rangement is a mopaloid slit on each side, with an angular sinus at the, 

 tail, and that the extra slits arc extremely irregular and secondary. In 

 Nutiallimij the plan, on the contrary, is perfectly regular, and PhaccUo- 



