398 MAZATLAN UNIVALVES 
with blackish mud, sometimes bearing round flat egg-cases, 
pierced in the middle. Long. '61, long. spir. °32, lat. *25, 
div. (anfr. sup.) 40°. 
Hab.— Bay of Guayaquil; Gulf of Magdalena, California, 
5—22 fm.; Minds.—Mazatlan; not uncommon; L’pool & 
Havre Coll. 
Tablet 1902 contains 5 sp. immature.—1903, 6 sp. adult.— 
1904, 2 sp. mended after fracture.—1905, 1 sp. with egg-cases.— 
1906, 1 sp. with operculum ; also 2 separate opercula, one 
normal, the other with sub-central nucleus. 
468, P Drittia HaANn.eyt, 2. s. 
2D. t. subacuminatd, nigra, epidermide tenut nigro-cinerea, 
induta ; anfr. ?xi. subplanatis ; canali infrasuturali angusto 
et totd superficie tenuissime spiraliter striatis ; carind parunt 
prominente puxta suturam ; costulis radiantibus concinnis, valde 
acutis, circiter xv. viz declivibus ; apertura nigra ; t. adolescente 
sinu parvo; t.adulté ?......... 
Somewhat resembles the young of D. luctuosa, but is known 
by the fine costz, continued nearly to the base and the infrasu- 
tural keel. It has some points in common with Defrancia 
celata, Hinds, but its analogies seem to be with D. aterrima, 
&e. The only specimen found (which has its upper whirls 
smooth) is not quite mature, and measures long. °38, long. 
spir. ‘24, lat. °15, div. 32°. 
* Hab.—Mazatlan ; 1 fresh sp., L’pool Col. 
Tablet 1907 contains the specimen. 
469. Drittia ————, sp. ind. 
Tablet 1908 contains a shell, too much rubbed for description, 
and a spiral fragment which may be conspecific ; reddish 
brown, with a white spiral band, It closely resembles a W. 
Indian species. Shell with 6 normal whirls, anda rounded 
vertex of 3 smooth whirls. ong. °35, lat. "14. 
Hab—Mazatlan; extremely rare, off Spondylus; Z’pool Col. 
470. Dritt1a ————, sp. ind. 
« Tablet 1909 contains a specimen, too much worn for des- 
ceription, of a small turrited species of about 7 whirls, measuring 
