191 



other, but sometimes they are nearly opposite. The surface is likewise 

 marked with prominent, rounded, oblique annular costaj, which are 

 indistinct on the ventral side, and frequently bifurcate at the nodes. 



The diameter of the last volution, a short distance from the ex- 

 panded aperture is about 15 lines ; diameter of base 3^ inches. 



Of this fine species, I have seen only the last and a portion of the 

 succeeding volution of an apparently mature shell, from which the 

 entire height may be estimated at not less than six inches. 



Found by Dr. G. G. Shumard at Chatfield Point, Navarro County, 

 associated with the preceding species. 



Genus Tukrilites, Lamarck. 



T. SPLENDIDUS, (n. sp.) Shell turretted, spire sinistral and dex- 

 tral, very much elevated ; spiral angle 23° ; volutions about ten, 

 strongly rounded, contiguous ; suture deeply excavated ; umbilicus 

 small, occupying a very small part of the diameter of the last volu- 

 tion ; aperture subcircular. A short distance behind the aperture is 

 a prominent ring, anterior to which the diameter becomes suddenly 

 contracted to the margin ; surface elegantly ornamented with promi- 

 nent rounded, simple and bifurcating ribs, which on the body volu- 

 tion commence at the margin of the umbilicus, and pass in an oblique 

 upward and backward curve, until they get near the suture, where 

 they are suddenly bent forwards. The number of ribs on the last 

 volution varies from twenty-four to twenty-eight, and they are here 

 wider apart and not so regular as on the turns of the spire. Ribs 

 bearing each two small elongated tubercles, one situated near the 

 inferior edge and the other near the middle. 



Length, twenty-one lines ; diameter of last volution seven lines. In 

 form and general appearance this beautiful Turrilite is similar to 

 T. catenatus, D'Orb., but differs in having a smaller umbilicus, in the 

 different position of the tubercles, and their smaller size. 



There are fragments of a Turrilite in the State Collection, which 

 appear to belong to this species, whose dimensions are double those 

 above given. 



Ripley Group, Chatfield Point, and near Corsicana, Navarro 

 County. 



T. HELiciNUS, (n. sp.) Shell sinistral, depressed conical, composed 

 of about five rounded, contiguous volutions ; spire very short ; spiral 

 angle about 80" ; suture very deeply impressed ; aperture subcircular ; 

 umbihcus deep, exhibiting the inner volutions, not as wide as the last 

 volution ; surface ornamented with prominent, sharp, annular costae, 

 which, on the last volution, pass obliquely backwards from the um- 

 bilicus to the suture. The costaa are usually simple, but occasionally 

 they bifurcate, and this generally occurs near the edge of the umbili- 

 cus ; about forty ribs may be counted on the last volution. The ribs 



