CLASS 11 



SCAPHOPODA 



50!) 



Family 1. Dentaliidae Gray. 



Scai)lwpoda having a conical foot with an encircling sheath expanded laterally and 

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

 anteriorly, sculptured or smooth. Ordovician to Recent. 



Dentalium Linn. (Figs. 838, 839). Characters those of the family. Beginning 

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

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

 About 275 fossil and 150 recent species known. Various authors have 

 attempted to subdivide the genus ui^on characters 'of the posterior slit 

 of the shell, but this has jDroved to vary widely even among individuals. 

 The following subgenera based upon the system of sculpture and 

 shape of the tube appear more stable : — 



Dentalium s. str. (Fig. 839). Shell with strong longitudinal ribs, apical 

 notch short or wanting. Eocene to Recent. 



Antalis Adams {Entalis, Gray non Sowb. ; 

 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. 



Heteroschisma Sirar. With longitudinal 

 riblets and a dorsal slit. Recent. 



Fissidentalium Fischer. Large and solid, 

 with many longitudinal ribs or striae ; a long 

 ventral slit usually present. Eocene to Re- 

 cent. Schizodcntaliu'ui Sowb., in which the 

 .slit is interrupted into a series of holes, is 

 probably a modification of this group. 



G-raj)tacme Pils. and Sharp. Surface with 

 close, fine longitudinal striae near ajjex only, 

 or throughout. Tertiary and Recent. 



Lacvidentalium Cossm. Arcuate, smooth, -'- -D- i^ntalis) Uckxi Nyst. Oli- 



.,, ,1 ,. 1 • T • i- gocene ; Wemneim, near Alzey. B, 



With growth-bnes only, circular in section, n. (Fnstiaria)lucula-Desh. Eocene; 



apex simple or notched. Silurian ? to Recent. Cuise la Mothe. Vi- '-', Posterior 



Ehabdus Pils. and Sharp. Smooth, thin, portion of same enlarged, showing 



Fi(!. 83S. 



ill 



slit. 



Fin. 839. 



Dentalium sex- 

 nnrjulare Lam. 

 Pliocene ; Asti, 

 Italy. 



glossy, nearly straight, sub - circular 

 section, apex entire. Recent. 



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

 with an inserted tube. Oligocene to Recent. 



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

 Eocene to Recent. 



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



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

 Cretaceous to Recent. 



Placjioglypta Pils. and Sharp. Surface with extremely oblique, sinuous, encircling striae 

 (Z>. undulatiim Mxmst.). Carboniferous to Trias. 



Family 2. Siphonodentaliidae Simroth. 



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

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

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

 Recent. 



den Bau und die Verwaiultschaftsbeziehungen der Solenoconchen. Zool. Jahrb., Abteil. fiir Anat. 

 mid Ontog., 1892, vol. v. [Bibliography, pp. ^M-ZiQ.]— Simroth, H., MoHusca, -in Bronn's 

 Classen und Ordnungen des Tierreiehs, vol. iii., 1893-95.— PiYsiry, //. A., and Sharp, B., Scapho- 

 poda, in Tryon and Pilsbry's Manual of Couchology, 1897-98, vol. xviL—BelNni, B., Revisione 

 delle Dentaliidae dei terrcni terziari e qnateniari d' Italia. Palaeont. Ital,, 1909, vol. xv. 



