190 



with three slender points, terminal ones divided, each branch bearing 

 several points, inner limb the longest; dorsal saddle as large or 

 larger than the superior lateral lobe, divided into two unequal 

 branches by an auxiliary lobe, the largest external and subdivided 

 into two branches by a short trifurcate lobe ; superior lateral lobe 

 broadest at base, having two or three branches on either side, the 

 terminal ones largest and bifurcated. 



Length two and a half inches, height at middle of last volution 

 about one inch. 



We are in possession of merely a fragment of this well-marked 

 species, consisting of about three fourths of the body volution. It 

 appears to be somewhat closely related to Scaphites iris, Conrad 

 (Jour. Acad. Nat. ScL Philad., N. S. vol. 3, p. 325, pi. 35, fig. 3), 

 but Mr. Conrad states that the sides of his species are flattened, and 

 the spaces between the nodes smooth, which characters do not apply 

 to our shell. 



Found near Dresden, Navarro County, in strata supposed to be of 

 the age of the Austin limestone. 



Genus Ptychoceras, D'Orbigny. 



P. Texanus, (n. sp.) Shell small and fragile, gently convex on 

 the sides, and flattened on the dorsum ; larger, or body portion, very 

 slightly tapering to the curve behind, and marked with a moderately 

 deep gutter on the ventral side, for the reception of the convex inner 

 side of the slender portion, the transverse section of which is broad 

 ovate ; surface marked with strong, simple, annular costte, which are 

 slightly oblique, wider than the spaces between, and on the dorsum 

 each bearing two slightly elongated nodes. 



This shell diff*ers from Ptychoceras (Hamites) annulifer of Morton 

 and P. Alortoni, Meek and Hayden, by its flattened form and larger 

 size, also from the former by its nodose ribs, and fi*om the latter by its 

 simple instead of divided costae. 



Formation and Locality. Cretaceous septariaB (Ripley Group), 

 near Chatfield Point and Corsicana, Navarro County. 



Genus Helicoceras, D'Orbigny. 



H. Navarroensis, (n. sp.) Shell large, dextral and sinistral, 

 composed of distant, free, convex volutions ; last volution rounded, 

 gradually enlarging to within a short distance of the aperture, where 

 it becomes suddenly expanded and flattened above and below ; dor- 

 sum ornamented with two revolving series of prominent nodes, one 

 series situated near the middle and the other at the base of the 

 volution. On the anterior third of the volution the nodes are flat- 

 tened, and the inferior ones project obhquely downwards and for- 

 wards. Tlie nodes of one series usually alternate with those of the 



