INSTITUTE OF SCIENCE, PHILADELPHIA. II3 



Fulgur pyrum var. aepynotum Dall. 

 Miocene of Alum Bluff, upper bed, Chattahoochee River, West Florida. 

 This remarkable form appears of large size and strong development (95 x 

 150 mm.) in the Lower Miocene, where the typical variety (incile) has round 

 and swollen whorls, contracted base and deep, wide sutural channel. It is 

 covered with fine sharp .spirals ; the shoulder is only emphasized in the young, 

 when it is tuberculous. In the adult it is rounded off in the last whorl. A 

 variety has a narrow sutural canal and wide, carinate shoulder, with low 

 tubercles on the keel. It is caiialifcnim of Conrad and may be regarded as 

 the offshoot from which proceeded the Wv'mg canaliculaium. Another variety, 

 cepynottiin ; which I suspect was confined to the young shells, which, probably, 

 if they attained full size, gradually lost their distinctive features on the later 

 whorls; has a medium sutural canal, an excavated, keeled shoulder, undulate 

 or subtuberculate and very coarse, broad spirals with wider interspaces. The 

 largest specimen I have seen is 30 x 50 mm. With these are intermediate 

 specimens leading directly to the excavatum form, though I have not yet seen 

 any genuine typical excavatum from the Miocene of Florida, though it appears 

 in South Carolina and northward. As time went on the excavatum, variable 

 at its best, on the whole changed in two respects: the whorl became rounder 

 and the channel at the suture less deep and wide. The height of the spire 

 and the coarseness of the spiral sculpture are always variable in these fossils, 

 hence I feel obliged to refer Gill's elongatmn to these species, though the 

 unique type seems to have been mislaid, and I can only judge from the figure 

 and description, which lend themselves to this view. 



F. excavatum was, on the whole, larger than the specimens of the recent 

 pyrum which I have seen, and this is also true of the Pliocene form from the 

 Caloosahatchie and Shell Creek, and the Myakka River Post-Pliocene speci- 

 mens collected by Mr. Willcox. The Pliocene form is nearer the recent form 

 than typical excavatum is, the Post-Pliocene still nearer, or practically identical 

 with the living shells. All through the series the height of the spire, the 

 angularity of the shoulder and the coarseness of the striation (especially in 

 the very young) are variable factors. The recent shells are more uniform in 

 their spiral sculpture than any of their fossil progenitors, but they differ simi- 

 larly in the height of the spire and the excavation of the sutural canal. I 

 feel that it is impossible to frame a .specific diagnosis that shall accurately de- 

 scribe the fluctuations of the four forms I have treated as varieties and at the 

 same time discriminate them. For this reason I have not regarded them as 

 entitled to specific rank. Beside those I have mentioned, there is a curious 

 variety in the Post-Pliocene which has the shell very pyriform, almost smooth, 

 with no keel on the shoulder and with a very narrow sutural channel. It 

 connects with the others by degrees. 



Beside the species above limited, I know of but two valid species of the 

 Sycotypus section of the genus. These are F. coro7iatum Conrad and its variety 



