22 PROCEEDINGS OF THE ACADEMY OF 



Its closest analogue is 21. primigenius, Hall, (Io. Rep. p. 720, pi. xxix. 11.) 

 M. ponderosus, Swallow, (Trans. Acad. Sci., St. Louis, i. p. 202). The aper- 

 ture, however, is broader, the spire less elevated and the columellar fold ap- 

 parently much less pronounced. 



From the lower bed of the yellow sandstones being, until the recent de- 

 scription of some specimens from the Hamilton Group of New York, (See Fif- 

 teenth Rep. N. Y. Reg., p. 48), the lowest known position of this section of 

 the genus. 



LOXONEMA, Phillips. 



Loxonema oligospira, n. sp. Shell small; whorls about six, rather rapidly 

 enlarging, convex exteriorly, with traces (on the cast) of vertical ridges, which 

 become most observable in the vicinity of the aperture ; suture deep ; body 

 whorl three-fifths the length of the shell, more rapidly enlarging than the 

 spire, gently convex on the outer side, more rapidly curved toward the base 

 which is somewhat umbilicately indented rapidly increasing in diameter 

 toward the aperture, which is thus rendered somewhat effuse in front. 



Height of shell -41 (100) ; height of body whorl -25 (61) ; diameter of body 

 whorl -29 (71) ; diameter of penultimate whorl - 16 (39). 



HOLOPELLA, McCoy. 



Holopella mira, ii. sp. Shell small, turrited ; whorls gradually and regu- 

 larly enlarging, seven or eight in number, of which four or five are generally 

 preserved, the apical ones, in numerous specimens, uniformly wanting ; 

 whorls sometimes slightly flattened on the exterior ; suture distinctly but not 

 deeply impressed ; body whorl regularly rounded beneath into a minute um- 

 bilicus ; aperture nearly circular, obtusely angulated behind, regularly rounded 

 in front ; peristome complete or slightly interrupted ; columellar lip without 

 a fold, very slightly excavated by the aperture. 



Height of shell about -24 (100) ; height of body whorl -11 (4G) ; diameter 

 of body whorl *14 (58) ; apical angle 35. 



This little shell occurs gregariously in calcareous layers of bed No. 3, and 

 also occasionally in sandstone No. 5. The exterior seems to be destitute of 

 natural ornaments, but the specimens in bed No. 3 are universally marked by 

 lines like cleavage cracks, running very obliquely across the several whorls, 

 their lower extremities being nearest the aperture. 



This fossil bears a close resemblance to Turritella (Holopella) gregaria and 

 conica, Sow., (Murch. Sil. Syst., pi. iii. fig. 1, f. and 8) from the old Red Sand- 

 stone, but it differs from both (See McCoy, Pal. Foss., p. 303,) in apparently 

 having no natural surface markings. 



NATICOPSIS, McCoy. 



Naticopsis depresscs, n. sp. Shell small ; spire of about four volutions, 

 scarcely elevated above the body whorl ; last whorl rapidly enlarging, espe- 

 cially in an obliquely transverse direction ; suture very shallow, giving the 

 upper side of the shell a general convexity ; width of last whorl at the aper- 

 ture three-fifths the transverse diameter of the shell ; aperture oval, rounded 

 anteriorly and posteriorly ; within, somewhat contracted on the inner side by 

 the broad, flattened columella ; surface marked by delicate lines of growth, 

 which, toward the suture, become, on the last whorl, fine, regular, elongated 

 nodes. Highest point of shell, when resting on its base, is on the last whorl, 

 near the junction of the outer lip with the penultimate whorl. 



Height of shell from antero-lateral margin of aperture obliquely to summit 

 of spire *50 (100) ; greatest transverse diameter -59 (118) ; width of body 

 whorl measured in the same direction *36 (72) ; altitude of shell when resting 

 on its base, in a direction nearly at right angles with the last measure *30 

 (60) ; length of aperture -37 (74) ; width '32 (64). 



ORTHOCERAS, Breynius. 



Orteoceras Whitei, n. sp. Shell annulated, very gradually tapering, with 



[Jan. 



