1 • n (5 . ] NATURAL .SCIENCES OF PHILADELPHIA. 165 



cealing entirely the umbilicus; edge of pillar flattened at entrance of 



canal, simulating a fold. 



This genus is characterized by a fairly low-spiral angle; vigorous 

 rugose, cancellate sculpture; a much inflated body and further 1- 

 much excavated and reflected inner lip, which conceal- an umbilicus. 

 Besides the Coon Creek species it is represented by an undescribed 

 species from Owl Creek, Mississippi, and another from Brightseat, 

 Maryland, and further by a species in the Senonian of Aix-la-Cha- 

 pelle. Germany. The German species was first described by Ntuller 

 in 1851 and assigned to the genus Rapa. Since then it has been 

 variously assigned by other palaeontologists to such genera as Fusus, 

 Pynila, Hemifusus, Pyropsis and finally to Tudicla by Holzapfel, 11 

 who discussed the species in 1888. A study of the description and 

 figures of the German form, together with the Coon Creek species 

 and specimens from the Maryland and Mississippi localities, indicate- 

 that these species belong to a well-defined group, and it seems advisable 

 to propose for their reception a new genus Hydrotribulus of the family 

 Buccinidee. In general aspect this genus resembles Pyrifusus, but 

 differs from it in having a shorter recurved anterior canal and a 

 pillar which is flattened and recurved in a unique manner at the 

 entrance of the canal. Tudicla has a much flatter spire, a more globose 

 body and a much more abruptly constricted, longer and straighter 

 canal. It differs from Strepsidura in characters of the anterior 

 canal and aperture and further by its characteristic rugose cancellate 

 sculpture. 



Hydrotribulus nodosus sp. nov. PI. XXIV, figs. 4 and 5. 



Description. — Shell fairly large and very heavy with a rugosely 

 cancellate sculpture; top-shaped in outline; spire rather low; its 

 altitude less than the length of the aperture, sides converging at an 

 angle of 70 degrees; whorls of conch five in number and rapidly 

 increasing in size to a much inflated body; whorls of conch obliquely 

 shouldered, the peripheral angle of the spire falling in front of the 

 medial horizontal; sculpture vigorous, both axial and spiral, 

 restricted almost entirely to the area in front of the periphery; 

 axials elevated and broadly rounded, sixteen in number on the body 

 whorl of the type, subequal in size and regularly spaced; spiral 

 sculpture of broad, elevated fillets, most prominent on the body; 

 subnodose at the intersections of the axials which they override. 



"Holzapfel, E., Palaeontographica, Band XXXTV, p. L06, Taf. xi, figs. 1-7. 



