294 TRANSACTIONS OF THE WAGNER FREE 



of which has been described by Professor Whitfield in his manuscript report 

 on the mollusks of this formation. The other was supposed by Conrad to be 

 identical with his Tiirbinopsis Hilgardi. This form differs from the ordinary 

 Modulus in having a deep, wide umbilicus ; but, since the recent species of 

 Modidus may be either imperforate or umbilicated, this is not a character of great 

 weight. The type of Pseudotroclms Heilprin is a typical and remarkably fine 

 species of Modulus. In most of the manuals Modulus is given merely as a 

 recent genus, but it has existed in America continuously since the Creta- 

 ceous. Monodonta basilea Guppy, from the older Miocene of Jamaica (Geol. 

 Mag. Dec. ii., vol. i. p. 442, pi. xvi. fig. 2, 1874), is a typical Modidus. 



Modulus turbinatus Heilprin. 

 Plate 18, figure 12. 

 Pseudotrochus turbinatus Heilprin, Trans. Wagner Inst. i. p. 114, pi. 16, fig. 57, 1887. 



Older Miocene of the Orthaulax bed at Ballast Point, Tampa Bay, Florida, 

 Willcox, Dall and Crosby. 



This fine species has been refigured, as the original figure was far from 

 satisfactory. 



Modulus 'Willcoxii n. s. 

 Plate iS, figure i a. 



Older Miocene of the Chipola beds, Northwest Florida, Burns. 



Shell large, strong, with two (or more) small, smooth nuclear and seven 

 subsequent sculptured whorls ; whorls with a blunt duplex carina, on which 

 the suture is wound ; spiral sculpture, above the carina, of five or six strong, 

 rather sharp, elevated ribs, subequal, with about equal interspaces ; below the 

 carina, on the base, are about seven more, growing stronger and flatter to- 

 ward the pillar ; these spirals are undulated by the intersection of numerous 

 transverse sulci in harmony with the lines of growth ; base flattish, sub- 

 conic ; aperture subquadrate ; outer lip sharp-edged, sharply Urate inside in 

 harmony with the spiral sculpture ; body with a thin callus ; pillar short, 

 bearing a broad and strong revolving lamella; umbilicus closed ; suture dis- 

 tinct, slightly turriculate. Alt. of shell 20 ; max. diam. 14 mm. 



Mr. Burns obtained but a single specimen of this fine species, which it 

 gives me much pleasure to dedicate to Mr. Joseph Willcox, to whose energy 

 and interest this investigation of our Southern Tertiary is largely due. 



Modulus compactus n. s. 

 Plate 22, figure 10. 

 Older Miocene of the lower bed at Alum Blu.ff, Chattahoochee River, 

 Florida, Burns. 



Shell small, turbinate, with a rather pointed apex and about six whorls 

 (nucleus lost), rapidly enlarging ; transverse sculpture of ten rounded ribs 



