NO. 2283. XEW PACIFIC COAST CHITONS— DALL. 515 



surface microscopically decussate without other sculpture ; internally 

 greenish, with a rather narrow jugal sinus and prominent sutural 

 laminae; intermediate valves polished, slightly mucronate, wholly 

 microscopicallj^ decussate, without other sculpture except two slender 

 simple ribs which border the lateral areas; internally greenish and 

 white with wide and shallow jugal sinus and narrow arcuate sutural 

 laminae. Length, 20; width, 11; height, 3 mm. 



Habitat. — Between Cape Pillar and Cape Horn, Tierra del Fuego ; 

 Stokes. Cat. No. 218734, U.S.N.M. 



In spite of its gloomy color this is a very elegant species. 



ACANTHOCHITONA ANGELICA, new species. 



Since the sculpture of all the species from the west coast is so very 

 similar this form perhaps may be best indicated by comparison with 

 the other known species. The valves are of a bright scarlet and 

 mucronate ; the tufts of bristles are w^hite and only moderatelj^ pro- 

 fuse, the girdle otherwise is covered with short grayish spines of 

 irregular length and plushlike aspect. 



From A. avicula Carpenter, it is distinguished by its more central 

 mucro in the posterior valve, its generally larger valves and narrower 

 girdle. Nearly the same ditferences separate it from A. diegeiwis 

 Pilsbry, and aragonites Carpenter. It has not the profuse silky 

 bristles of Pilsbry 's A. exquislta, nor the broad girdle and peculiar 

 sculpture of Sowerby's A. hirundiniformis. None of these species 

 has the intermediate valves so long axially in proportion to their 

 transverse width. The form of the valves is almost semicircular, the 

 jugal area axially striated and the remainder of the exposed surface 

 has the scaly sculpture usual in this genus. Length, about 11 ; width, 

 5 ; height, 3 mm. 



Habitat. — Angeles Bay, Gulf of California, W. J. Fisher. Cat. 

 No. 110346, U.S.N.M. 



TONICIA MIXTA, new species. 



Chiton of moderate size, mottled or streaked with light brown, 

 scarlet, gray, blackish and white, the back rounded, the valves 

 mucronate but not keeled, the gill rows ambient, the girdle with a 

 dense coating of short spinules with a few scattered longer spines; 

 anterior valve with 8 or 9 slits, posterior with 11 or 12, intermediate 

 valves with one or two, sometimes differing on opposite ends of the 

 same valve, the insertion plates striated ; anterior valve small, semi- 

 circular, more or less densely provided with small pustules and ir- 

 regularly distributed polished brown eyespots; there are faint indi- 

 cations of five radial threads which in some individuals might become 

 stronger; the surface of the whole shell is covered with microscopic 

 punctation; posterior valve with low central or post central mucro, 

 the central area with coarse axial nodulous threads, the posterior 



