PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 329 



lata; zona angusta, olivaceo-cinereo niaculata, confertim spinulis minutia 

 ornata, oculo nudo sublrevis ; subirricroscopio epidermis dorsalis pubes- 

 cens, stroma spiniilis rarioribus lateiitibus erectis; macro indistinct is 

 in summa tamen linea mediana valvarum intermediarnm snperne salens 

 decnrrit linearis, longitudinalis, argute incisus ; sinn jugali modico, alto, 

 haud laminato, conspicue spongiosa, snbgrimdis minimis, maxime spon- 

 giosis; v. ant. 11-, post. 11-, ceutr. 1-fiss. Branchiae circ. 22, snbambi- 

 entes. Lon. 16, Lat. 5 mm. Div. 110°. 



Hab. — Shantar Bay, Okhotsk Sea, Midd.; Aleutian Islands eastward 

 to Sitka Harbor, low water to 12 fathoms on stones and shells; Dall! 

 Xinety -three specimens examined. 



This very remarkable species is very prettily marbled with olive, 

 chestnut, and blue; the girdle generally dark olive, dashed with ashy 

 spots and in fine specimens having a pubescent appearance. The slit 

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

 visible from within. The branchiae appear to reach nearly to the head. 

 It is quite possible that it may reach as far south as Puget Sound. 



The soft parts are yellowish white. The gill-rows extend three-fourths 

 of the length of the foot forward from their posterior termination, and 

 each contains about twenty-two branchiae. Mantle-edge thick, plain; 

 veil small, plain. Muzzle small, plain, with two large squarish lappets 

 at the posterior corners. The supposed oviducts open on each side 

 through a small rounded papilla in the vicinity of the third or fourth 

 Jbranchia counting forward, and between the line of the gill-row and 

 the side of the foot. 



Genus CHiETOPLEUKA Shuttleworth. 



Chwtopleura Shuttlew. Bern. Mirth. Jimi 1853. Type Chiton Perurianits Lain. 

 <Ch(vtopleura H. & A. Adams, Gen. Rec. Moll, i, p. 475, 1854. 

 <Acanthopleura Gray, P. Z. S. 1847, p. 67. 



Testa Ischnochitoni similis; zona pins minus ve pilosa. Branchiae 

 ambientes. 



Chaetopleura Hartwegii. 



Chiton Hartwegii Carpenter, P. Z. S. 1855, p. 231. 



Trachydermon Hartwegii Opr. Suppl. Rep. Br. Assoc. 1863, p. 649. 



C. t. colore olivaceo, cinereo sen rufo-fusco sen cupreo-viridi, srope 

 eleganter maculoso; intns, intense caeruleo-viridi ; mucrone mediano 

 satis elevato; valvis singulis tnmentibus, eleganter arcuatis, apicibas 

 conspicuis, suturis marg. distinctis; ar. diag. hand nisi costis tuincnti- 

 bus subobsoletis discernendis ; tota snperficie super grannlis minimis, 

 sub lente solum distingnendis, granis parvis ubique sparsis; super ar. 

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

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



