io6 Bulletin 4 a^o. 



It shows that between the three spiral lines of each whorl there 

 are sometimes as many more, somewhat less conspicuous, still very 

 evident. Another specimen shows the columellar plaits as in 

 fig. 10, pi. 10; they are, however, somewhat more acute. On the 

 base of each whorl there is a strong, median spiral ridge. 



A fragment of a large whorl presumably of this species was 

 found in the uppermost bed of the Midway limestone as exposed 

 on Chattahoochee river at Ft. Gaines. 



Cerithhmi gainesensis n. sp., PI. 11, fig. i. 



Specific characterization. — Size and general form as indicated 

 by the figure; whorls about 13; i to 10 with 15 to 25 low ribs 

 nearly equal to the interspaces, crossed by three strong, subequal, 

 primary spirals, between which there are in well preserved speci- 

 mens thread-like lines of secondary order; sometimes granular at 

 junction of the ribs and primary spirals; sides of whorls nearly 

 regularly convex but with a tendency to become slightly con- 

 stricted for a little distance below the suture, then gradually 

 rounding in the middle and slightly gibbous below, the varia- 

 tion from a circular curve, however, is very slight; the whorls 11 

 and 12 are but slightly ornamented, generally with a varix or 

 two and with a few slight indications of ribs and with three, or 

 four faint spirals; the middle one is sometimes on a very slight 

 carination; body whorl with generally one varix. with anterior 

 and posterior canal, and with outer lip sharp on the edge but 

 thickening rapidly within. 



In some specimens there are four primary spirals on each whorl. 



Dall has described a fragment of a spire of a Cerithiutn from 

 Jacksonboro, Ga., under the name of C. platynema. At first I 

 was inclined to think that fragment might possibly be gaines- 

 ensis, for the ribbing and three strong spirals with finer lines 

 seemed to agree very well with Ball's species; but I fail to find 

 any trace of the broad plain spiral at the base of each lower 

 whorl as is noted in both Ball's figure and description. Mr. 

 Hubbard and I collected a large number of specimens of gaines- 

 ensis, and although all are in the forms of moulds and casts, 

 gutta-percha impressions of them show every portion of the 

 species many times. Common. 



Locality. — GEORGIA: Uppermost Midway as exposed on the 

 Chattahoochee at Ft. Gaines. 



Type. — Paleontological Museum, Cornell Univ. 

 Cerithium globoleve n. sp., PI. 11, fig. 2. 



specific characterizatio7i. — Size and general form as indicated 



