MAZATLAN UNIVALVES 499 
Tablet 2400 contains 2 young shells and a fragment which 
probably belong to this species. The first 3 whirls are smooth 
and rather globose; then fine sharp ribs appear, which soon 
become fenestrated by spiral lines which increase in number, 
and finally develop granules at the intersections. 
JTab.—Panama, 1 sp. C. B. Adams.—Mazatlan ; portions of 
5 specimens, off Spondylus; L’pool Col. 
632. Nassa Pversicotor, C. B. Ad. 
Pan. Shells, pp. 66, 305, no. 55.—Rve. Conch. Ic. pl. 17, f. 110. 
_(Nassa) Uzita versicolor, H. & A. Ad. Gen. i. 120. 
Tablet 2401 contains fragments which may belong to this 
speciés. , 
Hab.—Taboga, common, C. B. Adams.—? Mazatlan ; extremely 
rare, fragments off Spondylus; L’pool Col. 
633. NAssA CREBRISTRIATA, 7. S. 
N. t. acuminata, flavido-fuscd, solidiore ; anfr. normalibus 
vi. parum rotundatis, suturé distincta ; costis circiter x. acutis, 
distantibus, sparsim varicosis, aperturam versus haud obsoletis ; 
striulis spiralibus ereberrimis, exillimis ornatad ; apertura sub- 
votundata ; labro varicoso, intus crebre lirulato, juxta canalem 
lira extante; labio haud reflexo, parwn extante ; tubereulo 
parietali parvo ; plicd acuta canalem recurvatum valde extan- 
tem definiente. 
The only specimen found, covered with Bryozoa in the 
upper whirls, has the aspect of N. incrassata, from which and 
cognate species it differs in the extreme fineness of the spiral 
sculpture. Long. 54, long. spir. ‘32, lat. °3, div. 37°. 
Hab.—Mazatlan ; 1 fresh sp. L’pool Col. 
Tablet 2402 contains the specimen. 
634. Nassa — , sp. ind. (f.) 
Tablet 2403 contains a small, imperfect specimen resembling 
N. erebristriata ; but red, with the spire less elevated, and the 
ribs broad and blunt. 
Hab.—Mazatlam; 1 sp. off Spondylus ; L’pool Col. 
