326 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



puckered up in front, with tlio posterior corners produced into lajipets. 

 There is no veil. Oviducts not clearly made out. The ovarian openings 

 are simple and close on each side of and a little behind the aims, from 

 which a ridge extends in front of them on each side. But there appear, 

 also, to be two openings in the vicinity of the fourth or fifth branchia 

 from the posterior end of the gill-rows, olie on each side. The contracted 

 condition of the specimens, from the effect of the alcohol in which they 

 were preserved, prevented a satisfactory confirmation of these appear- 

 ances. 

 Tonicella lineata. 



Chiton Uneatus Wood, Gen. Concli. p. 15, pi. 2, f. 4-5, 1815. — Midd. Mai. Eoss. 

 i, p. 109, t. xii, f. 8-9, 1847. — Keeve, Coucli. Icon. Mon. CMtou, j)L vii, f. 

 33, 1847. 



Tonicia lineata H. & A. Adams, Gen. Eec. Moll, i, p. 474, 1854. 



Chiton {Hamachiton, Stvnosemus) lineata Midd. Mai. Eoss. i, p. 34. 



Tonicella lineata Carpenter, MS. 



T. t. mucrone antice mediano, satis elevato; intus, v. ant. 9-12-, v. 

 post. 8-10-, V. centr. l-fissataj dent, obtusioribus (t. jun. acutis), posticis 

 curtioribus, vix iiiterdiun rugulosis; subgrundis curtis, spongiosis ; sinu 

 angusto, alto, Isevi, angulato; branchiis mediauis; testa externa subele- 

 vata, tegmentum Iseve, areis lateralibus vix distinctis; flavum aut fiis- 

 cum, Uneolis albis pictum, zona coriacea, oculo nudo la?vis. Lon. 30, 

 Lat. 15 mm. Div. 120^. 



Sal). — Prom Bering Strait south, on both coasts j westward to Japan 

 and the Okhotsk Sea; eastward to the Bay of Monterey, Cahfornia, and 

 including the whole Aleutian chain; low water to CO fathoms. Two 

 hundred and eighty specimens examined of the typical form. 



The painting of this very characteristic species is very variable, even 

 on different valves of the same individual. Xothing can apj^ear more 

 distinct than the coloration of tyjiical specimens of some varieties, but 

 in a large series the differences do not hold equally good. The number 

 of slits is also somewhat variable, occasional abnormal or injured speci- 

 mens having only six or seven shts in the tail- valve. But fine and nor- 

 mal specimens of both varieties show no more than individual variations. 



Middendorf, while pointing out the distinctions between the following- 

 species and T. marmorea, appears to have overlooked the connection be- 

 tween the former and T. lineata, and his description does not always 

 agree with his figures. 



From Tonicia lineolata Sowerby, from South America, beside the in- 

 ternal generic characters, the exterior differs by the absence of punctures 

 and raised granules at the sides. 



T. mhmarmorea is further distinguished from lineata by the somewhat 

 raised Uiteral areas, Avhich are hardly perceptible in the present form. 

 It is one of the handsomest Alaskan Chitons. The southern specimens, 

 especially those from Monterey, generally have the yellow and brown 

 lines marginated with blue, which produces a peculiar color-effect. 



