24 Calvin Goodrich 



Description: Shell smooth, ovately gibbous, thick, yellowish-brown; spire short; 

 whorls four, flattened; columella thickened above; aperture large, ovate, white. 



Habitat : Alabama. 



Diameter, .44; length, .64 of an inch. — Lea, 



In incisum the fissure is shallow and oblique. It is as deep as y^A mm. 

 in specimens from Weduska Shoals. It is most shallow in specimens from 

 Butting Ram Shoals down to Wetumpka, not exceeding 2^ mm. in depth. 

 The girdle, which represents the material filling the fissure as growth pro- 

 ceeds, is usually well-marked when it is noticeable at all, particularly to- 

 ward the end of growth of adult individuals. 



The shell is heavy, broadly rounded at the shoulder, frequently with a 

 broad constriction around the center of the whorl. Hinkley (2, p. 40) 

 speaks of incisum as never nodulous. Occasional specimens do have nodes 

 at the shoulder, but these markings appear to be without significance. The 

 largest shell observed measures 22 x 14^^ mm. The growth lines are usual- 

 ly fine and regular and these are often crossed by discontinuous transverse 

 lines, plainest at the top of the whorl. Of 78 shells from one lot from 

 Wetumpka, 11 showed revolving folds of more or less prominence. The 

 folds are seldom present in incisum coming from farther up the river. Color 

 varies from olive-ocher to cinnamon-brown. Bands occur much more com- 

 monly than not. Of 77 banded shells from Wetumpka, 74 had a band at the 

 top of the whorl, one at the periphery and a third at the base. This is the 

 prevailing banding formula in the species from other localities. The aper- 

 ture is ovate, varying slightly. The columella in adults is white, rather wide, 

 broadly rounded and regularly curved vertically, being thickened into a 

 small node at the mouth of the fissure. The outer lip is sharp-edged, 

 sinuous. 



Juveniles are conic, angulated at the base, having the whorls flat and 

 without carinae. A channelled sinus, present in all the young examined, is 

 much more pronounced than in the case of adults. The fissure begins with 

 the third whorl and is easily distinguished in the fourth. Six or seven 

 whorls for the fully-grown shell are indicated. 



The range of incisum is from AWduska Shoals, Shell)}- County, to We- 

 tumpka, Elmore County. 



Lea's type is a narrow, somewhat constricted form of the Wetumpka 

 aspect. His virens is a young shell. Curia Mighels ap])ears to me to be 

 readily recognizable from the description. I examined the type of huddii 

 Lea, the locality for which is given in«rror as Tuscaloosa, but felt uncertain 

 about the identification. Mv. W. B. Marshall of the National Museum 

 kindly furnished me later with an excellent photograph and I can say with 

 confidence that the shell is the same as incisum. The cut in Try on (6. p. 

 371) could not have been made from the type. The constriction in consfrict- 

 tim is fairly common to the species. FunicuJatuuh Lea is a deformed mol- 

 lusk. 



At the mouth of the Yellowleaf Creek of Chilton County, Mr. T. H. 

 Aldrich took numbers of a small form of Gyrotoma which, though suggestive 

 of zvalkeri because of its delicacy, I assign to incisimi on account of the 

 deeper fissure. These shells have a kind of family resemblance to Anculosa 

 aldrichi H. H. Smith, taken at the same locality. This Anculosa also is 



