PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 329 



lata; zona angusta, olivaceo-cinereo maculata, confertini spinulis minutis 

 ornata, oculo undo subLevis 5 submicroscopio epidermis dorsalis piibes- 

 ceus, stroma si)imdis rarioribiis latqjitibus erectis; mucro indistinctis 

 iu siimma tameu linea mediaua valvanim intermediarum superne sulcus 

 deciirrit linearis, longitudiiialis, argute iucisus; siuu jugali modico, alto, 

 baud lamiuato, conspicue spougiosa, subgruudis minimis, maxime spon- 

 giosis; V. ant. 11-, post. 11-, centr. 1-liss. Brancbiai circ. 22, subambi- 

 entes. Lon. 16, Lat. 5 mm. Div. 140°. 



Hah. — Sbantar Bay, Okbotsk Sea, Midd. ; Aleutian Islands eastward 

 to Sitka Harbor, low water to 12 fatboms on stones and sbells; Dall! 

 Niuety-tbree si^ecimens examined. 



Tbis very remarkable species is very prettily marbled witb olive, 

 cbestnut, and blue; tbe girdle generally dark obve, dasbed witb asby 

 spots and in fine specimens baving a pubescent appearance. Tbe slit 

 is occupied by a cartilaginous substance of a dark brown color, most 

 visible from witbin. Tbe brancbiae appear to reacb nearly to tbe bead. 

 It is quite possible tbat it may reacb as far soutb as Puget Sound. 



Tbe soft parts are yellowisb wbite. Tbe gill-rows exteud tbree-foui'tbs 

 of tbe lengtb of tbe foot forward from tbeii* posterior termination, and 

 eacb contains about twenty-two brancbiaj. Mantle-edge tbick, plain ; 

 veil small, plain. Muzzle small, plain, witb two large squarisb lappets 

 at tbe posterior corners. Tbe supx^osed oviducts open on eacb side 

 tbrougb a small rounded papilla in tbe vicinity of tbe tbird or fourtb 

 brancbia counting forward, and between tbe line of tbe gill-row and 

 tbe side of tbe foot. 



Genus CH.^TOPLEUEA Sbuttlewortli. 



CliwiopJeura Slitittlew. Bern. Mittli. Jaui 1853. Tj-pe Chiton Penirianus Lam. 

 <^Clia',topleara H. & A. Adams, Gen. Eec. Moll, i, p. 475, 1854. 

 <^Acantliopleura Gray, P. Z. S. 1847, p. 67. 



Testa Iscbnocbitoni similis; zona plus minusve pilosa. Brancbiae 

 ambientes. 



Chaetopleura Hartwegli. 



Chiton Eartwegii Carpenter, P. Z. S. 185.5, p. 231. 



Trachydermon Hartwcgii Cpr. Suppl. Eep. Br. Assoc. 1863, p. 649. 



C. t. colore olivaceo, cinereo sen rufo-fusco seu cupreo-"viridi, saepe 

 eleganter maculoso; intus, intense Cieruleo-viridi; mucrone mediano 

 satis elevato; valvis smgulis tumentibus, eleganter arcuatis, apicibus 

 conspicuis, suturis marg. distinctis; ar. diag. baud nisi costis tumenti- 

 bus subobsoletis discernendis ; tota superficie super granulis minimis, 

 sub lente solum distinguendis, granis parvis ubique sparsis ; sui)er ar. 

 diag. et v. term, granis majoribus irregulariter verrucosis ; intus v. post. 

 9-12-, ant. 10-11-, centr. 1-fissatisj dent, solidis, obtusis, interdum subru- 



