278 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Ischnochiton newcombi Carpenter, 1892 
Tryon and Pilsbry, Manual of Conchology, 14:120. 
Shell small, wide, tumid, with obtuse, rounded jugum. Mucro median, 
rather elevated. Ashy or olivaceous, elegantly clouded; central areas and 
entire surface granulated, the granules being quincuncially arranged, close 
and regular; lateral areas scarcely defined, having about 4 lines of tu¬ 
bercles which are hardly elevated. Posterior valve having about 30, 
anterior valve 40 such lines. Interior: posterior valve having 12, median 
1, anterior valve 11 slits; teeth acute; eaves apparent; sinus wide, short, 
scarcely laminate. Girdle imbricated with large striated and rather regular 
scales. Length, 8 H ! breadth, 6 l A mm.; divergence, 100°. (Carpenter.) 
(Tryon and Pilsbry, Manual of Conchology.) 
Type in ? Type locality, Catalina Island, California. 
Range. Known only from the type locality. 
Ischnochiton serratus Carpenter, 1864 
Annals and Magazine of Natural History, 13:315. Tryon and Pilsbry, Manual of 
Conchology, 14:122; 15:78; PI. 16, figs. 42-46. 
I. testa parva, cinerea, olivaceo hie et illic, praecipue ad suturas, punc¬ 
tata interdum sanguineo maculata; ovali, subdepressa, suturas indistinctis; 
tota superficie minutissime granulata; ar. diag. valde distinctis, costis latis- 
simis obtusis ii.-v. munitis, interstitiis nullis; marginibus posticis eleganter 
serratis; ar. centr. costis acutis, parallelis, utroque latere circ. xii.; jugo 
obtuso, haud umbonato; costis transversis, subradiantibus, fenestratibus, 
interstitiis impressis: mucrone mediano, obtuso; valv. term, costis obtusis 
ut in ar. diag., circ. xx.; intus valvarum mediarum lobis bifissis, termi- 
nalium circ. ix.-fissis; lobis suturalibus magnis; limbo pallii squamis majo- 
ribus, imbricatis, vix striatulis. Long., 34; lat., 2 poll. (Carpenter.) 
Shell small, ashy, dotted here and there and especially at the sutures 
with olive, sometimes spotted with red; oval subdepressed, the sutures 
indistinct; entire surface most minutely granulated; lateral areas strongly 
defined, provided with two to five very wide, obtuse ribs, no interstices; 
posterior margins elegantly serrated. Central areas having about 12 acute 
parallel ribs on each side; jugum obtuse, scarcely umbonate; with subradi¬ 
ating latticing ribs, interstices impressed. Mucro median, obtuse. End 
valves having about 20 obtuse ribs, like the lateral areas. Interior: median 
valves bifissate, end valves with about 9 slits. Sutural plates large. Girdle 
imbricated with large, scarcely striated scales. (Tryon and Pilsbry, Man¬ 
ual of Conchology.) 
Type in ? Type locality, Cape San Lucas, Lower California. 
Range. San Diego, California, to Gulf of California. 
[880 ] 
