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. 

 Sab. Panama, 1 sp. C. B. Adams. Mazatlan ; portions of 



5 specimens, offSpomiylus ; IS pool Col. 



632. NASSA PVERSICOLOB, C. B. Ad. 



Pan. Shells, pp. 66, 305, no. 55. Rve. Conch. Ic. pi. 17, f. 110. 

 (Nassa) Uzita versicolor, H. fy A. Ad. Gen. i. 120. 



Tablet k . } 401 contains fragments which may belong to this 

 species. 

 Hob. Taboga, common, C. S. Adams. ? Mazatlan; extremely 



rare, fragments off Spondylus ; L'pool Col. 



633. NASSA CEEBEISTKIATA, n. s. 



N. t. acuminatd, flavido-fuscd, solidiore ; anfr. normalibus 

 vi.parum rotundatis, suturd distinctd ; costis circiter x. acutis, 

 distantibus, sparsim varicosis, aperturam versus hand obsoletis ; 

 striulis spiralibus creberrimis, exillimis ornatd ; aperturd sub- 

 rotundatd ; labro varicoso, intus crebre lirulato, juxta canalem 

 lira eoctante ; labio hand reflexo, parum extante ; tuberculo 

 parietali parvo ; plied acutd 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*. 

 Hob. Mazatlan ; 1 fresh sp. Upool Col. 



Tablet 2402 contains the specimen. 



634. NASSA , sp. ind. (f.) 



Tablet 2403 contains a small, imperfect specimen resembling 

 N. crebristriata ; but red, with the spire less elevated, and the 

 ribs broad and blunt. 

 Hab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



