298 TRANSACTIONS OF THE WAGNER FREE 



Csecum floridanum Stimpson. 



C. floridaftmn Sim., Proc. Bost. Soc. Nat. Hist. iv. p. 112, 1851 (young shell). 

 C. irregidare De Folin, Journ. de Conchyl. xv. p. 46, pi. 3, fig. 6, 1867 (Bahia). 

 C. annulatmn Emmons {non Brown, 1S44), Rep. Geol. N. Car., p. 274, fig. 190, 1858. 



Newer Miocene of North Carolina, Emmons ; Pliocene of the Caloosa- 

 hatchie, Dall ; living in shoal water from North Carolina south to Florida, the 

 Antilles and the northeast coast of South America to Bahia. 



This shell in the adult state is recognizable by its large size, numerous 

 annulations (of which a few near the aperture are more distant and much 

 stronger than the rest) and fine longitudinal striae, noticeable especially 

 between the rings. The plug has a slender mucro, set asymmetrically to 

 the right and projecting from a nearly flat surface. 



Caecum floridanum var. compactum Dall. 

 Plate 20, figure 9 b. 



Newer Miocene of the Cape Fear River, N. C, at Mrs. Purdy's marl- 

 bed, Johnson ; Pliocene of the Caloosahatchie, Dall. 



This form has the rings more closely set, so that the interspaces except 

 near the mouth are visible merely as fine lines. In the young stages of the 

 shell the annulations are often quite widely separated as described by Stimp- 

 son, but they are more close-set in the adult, and in this variety they touch 

 except at the anterior part of the shell. 



Csecum eoronellum n. s. 

 Plate 20, figure 11 a. 



Newer Miocene of Cape Fear River, N. C, at Mrs. Purdy's marl-pit, 

 Johnson ; Pliocene of the Caloosahatchie, Dall ; living on the coast of North 

 Carolina, twenty miles off Cape Hatteras in fifteen fathoms, U. S. Fish 

 Commission. 



Shell in the adult stage attaining a rather large size, rather thin, not much 

 tapered, with about twenty-four equal, little-raised, elevated, longitudinal 

 threads, with equal or wider interspaces; transverse sculpture of distinct, wavy 

 lines of growth, stronger near the posterior end ; the tube near the adult aper- 

 ture is suddenly enlarged, forming a stout ring around the aperture; the tube 

 is not constricted behind the ring, and the aperture looks somewhat 

 obliquely downward ; margin of the aperture sharp, distinctly crenulated or 

 denticulated by the ends of the longitudinal threads; operculum? posterior 

 end with the margin simple ; plug nearly hemispherical, with a very small 

 mucro at the extreme right-hand edge ; surface glistening when perfect, the 

 young with a much-flattened plug, with a very slender, rather long mucro, 

 which in the adult is generally worn down. Measurements of two specimens 

 give the length A, 3.75 ; B, 5.5 ; max. diam. of aperture. A, 0.9 ; B, 1.4 ; diam. 

 of posterior end, B, i.O mm. 



