CLASS ir 



SCAPHOPODA 



509 



Family 1. Dentaliidae Gray. 



Scaphopoda havimj a conical foot ivith an encircling sheath expanded laterally and 

 interrupted dorsally. Shell tubulär, curved, regularly tapering throughout, not contracted 

 anteriorly, sculptured or smooth. Ordovician to Eecent. 



DentaUum Linn. (Figs. 838, 839). Characters those of tlie family. Beginning 

 with a few species in the Ordovician, the number increases slowly until the Cretaceous. 

 A great acceleration then ensues, wliich continues to the present. 

 About 275 fossil and 150 recent species known. Various autliors liave * 

 attempted to subdivide tlie genus upon cliaracters of tlie posterior slit 

 of the Shell, but this has proved to vary widely even aniong individuals. 

 The following siibgenera based upon the system of sculpture and 

 shape of the tube appear more stable : — 



DentaUum s. str. (Fig. 839). Shell with streng longitudinal ribs, apical 

 notch Short or wanting. Eocene to Recent. 



Antalis Adams {Entalis, Gray non Sovvb, ; 

 Entaliopsis Newton and Harris) (Fig. 838, 

 A). Shell with longitudinal riblets or Striae 

 at least in the young ; apex with a short 

 ventral slit and a sheath. Cretaceous to 

 Recent. 



HeteroscMsma Simr. With longitudinal 

 riblets and a dorsal slit. Recent. 



Fissidentaliuvi Fischer. Large and solid, 

 with many longitudinal ribs or Striae ; a long 

 ventral slit usually present. Eocene to Re- 

 cent. Schizodentalium Sowb., in which the 

 slit is interrupted into a series of holes, is 

 probably a modificatiou of this group. 



Gra-ptacme Pils, and Sharp. Surface with 

 close, fine longitudinal Striae near apex only, 

 or throughout. Tertiary and Recent. 



La^videntalium Cossni. Arcuate, smooth, 

 with growth-lines only, circular in section, 

 apex simple or notched. Silurian ? to Recent. 



Rhahdus Pils, and Sharp. Smooth, thin, 

 glossy, nearly straight, sub - circular in 

 section, apex entire. Recent. 



Upisiphon Pils, and Sharp. Small and very slender, smooth, thin, the apex generally 

 with an inserted tube. Oligocene to Recent. 



Compressidcns Pils, and Sharp. Small, much tapering, vertically compressed, smooth. 

 Eocene to Recent. 



Lohantale Cossm. Shell compressed, with two internal longitudinal ribs. Eocene. 



Fustiaria Stol. (Fig. 838, B, C). Shell with a very long and linear ventral cleft posteriorly. 

 Cretaceous to Recent. 



Plagioglypta Pils, and Sharp. Surface with extremely oblique, sinuous, encircling Striae 

 {D. undulatum Münst.). Carboniferous to Trias. 



A, D. (Antalis) kickxi Nyst. Oli- 

 gocene ; Weinheim, near Alzey. B, 

 D. {Fustiaria) lucida Desh. Eocene ; 

 Cuise la Mothe. i/i- 6', Posterior 

 portion of same enlarged, showing 

 slit. 



Fio. 839. 



DentaUum sex- 

 angulare Lam. 

 Pliocene ; Asti, 

 Italy. 



Family 2. Siphonodentaliidae Simroth. 



Scaphopoda having the foot either expanded distally in a symmetrical disk with 

 crenate continuous edge, or simple and vermiform, without developed lateral processes. 

 Shell small and generally smooth, often contracted towards the mouth. Cretaceous to 

 Recent. 



den Boa und die Verwandtschaftsbeziehungen der Solenoconchen. Zool. Jahrb., Abteil, für Anat. 

 und Ontog., 1892, vol. v. [Biltliography, pp. 38i-dS6.]— Simroth, H., Mollusca, in Bronn's 

 Classen und Ordnungen des Tierreichs, vol. iii., 1893-95. — Pilsbry, H. A., and Sharp, B., Scapho- 

 poda, in Tryon and Pilsbry's Manual of Conchology, 1897-98, vol. xvii. — Bellini, li., Revisione 

 delle Dentaliidae dei terreni terziari e quaternari d' Italia. Palaeont. Ital., 1909, vol. xv. 



