MARYLAND GEOLOGICAL SURVEY 195 



JSTassa peralta (Conrad). 

 Plate XLIX, Figs. <), 10. 



JVassa irivittata Conrad, 1830, Jour. Acad. Nat. Sci. Phila., vol. vi, 1st ser., p. 211. 

 Buccinum trivittatum Conrad, 1843, Proc. Nat. Inst., Bull, ii, p. 186. 

 Buccinum trivittatnm Lyell, 1845, Quart. Jour. Geol. Soc. London, vol. i, p. 431. 

 Buccinum Irivitaturii Lyell, 1846, Proc. Geol. Soc. London, vol. iv, p. hhh. 

 Tritia trivitata Meek, 1S64, Miocene Check List, Smitli. Misc. Coll. (183), p. 30. 

 Ptychosalpinx [Tritiaria) peralta Conrad, 1868, Amer. Jour. Conch., vol. iii, p. 364, 



pi. xix, fig. 5. 

 rtychosalpinx {Tritarla) peralta Tryon, 1883, Manual of Conchology, vol. iv, p. 8, 



pi. iii, tig. 31. 

 Nassa irivittata Heilprin, 1884, U. S. Tertiary Geology, pp. .58, 61. 

 Nassa {Tritia) Irivittata Clark, 1888, Johns Hopkins Univ. Circ, vol. vii, p. 66. 

 Xassa trivittata Clark, 1891, Johns Hopkins Univ. Circ, vol. x, p. 107. 

 Nansa peralta Harris, 1891, Amer. Geol., vol. viii, p. 174. 



Description. — " Elongate turrited, whorls 8, longitudinally ribbed and 

 with revolving impressed lines, about 5 in number on the penultimate 

 volution; above near the suture on all the whorls there is a broader im- 

 pressed line, which divides the ribs and forms a tuberculous ridge around 

 the summits of the whorls; ribs narrow, numerous; spire acuminate." 

 Conrad, 1868. 



The body whorl is often much more expanded than any of the other 

 whorls. The number of ribs on the body whorl (20-25) is character- 

 istic of the species. The suture is deeply impressed. 



The synonomy of this species has been the subject of an article by 

 Professor Harris (see above), in which the bibliographic history of the 

 species has been discussed in great detail. 



Length, 20 mm.; diameter, 9 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver, Cove Point, 

 Langley's Bluff. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Philadelphia i^cademy of Natural Sciences, U. S. National Museum, 

 Cornell I'niversity, Wagner Free Institute of Science. 



Nassa peraltoides n. sp. 



Plate XLIX, Fig. 11 



Description. — Shell small, six-whorled; whorl? gently convex; suture 

 very distinct; lalnum with a thick callosity and with a tooth at the upper 



