CLASS II SCAPHOPODA 431 
imperfectly known to justify its reference to the Scaphopods, or even to the 
Mollusca. 
Family 1. Dentaliidae. Gray. 
Scuphopoda having a conte foot with an enctreling sheath expanded laterally and 
interrupted dorsally. Shell tubular, curved, reqularly tapering throughout, not contracted 
anteriorly, sculptured or smooth. Ordovician to Recent. 
Dentalium, Linn. (Figs. 789, 790). 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 3 
attempted to subdivide the genus upon characters of the posterior slit 
of the she, but this has proved to vary widely even among individuals. 
The following sub-genera based upon the system of sculpture and shape 
of the tube appear more stable :— 
Dentalium, s. str. (Fig. 789). Shell with strong longitudinal ribs, apical 
notch short or wanting. Eocene to Recent. 
Antalis, Adams (Eitalis, Gray non Sowb. ; 
Entaliopsis, Newton and Harris), (Fig. 
790, 4). Shell with longitudinal riblets or 
striae at least in the young; apex with a 
short ventral slit and a sheath. Cretaceous 
to Recent. 
Heteroschisma, Simr. 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 
Recent. Schizodentalium, Sowb., in which 
the slit is interrupted into a series of holes, 
is probably a modification of this group. 
| Graptacme, Pils. and Sharp. Surface with 
close, fine longitudinal striae near apex only, 
or throughout. Tertiary and Recent. 
Laevidentalium, Cossm. Arcuate,smooth, 4, D. (Antalis) Kickat, Nyst. Olig- 
A B (6 





G. 790. 

ae 4 Fic. 789 
: ts . d Bouaee St Ae ige A : ocene; Weinheim, near Alzey. 2B, pees 
with growth-lines only, circular in section, i (Buatiapia) niciddsDeshe Wobene: Déntalitmees 
apex simple or notched. Silurian ? to Recent. Cuise la Mothe. 1/;. C, Posterior angulare, Tam. 
Lthabdus, Pils. and Sharp. Smooth, portion of same enlarged, showing Pliocene; Asti, 
glossy, nearly straight, sub-circular in section, S!t- Italy. 
apex entire. Recent. 
Episiphon, Pils. and Sharp. Small and very slender, smooth, the apex generally with an 
inserted tube. Oligocene to Recent. 
Compressidens, Pils. and Sharp. Small, much tapering, vertically compressed, smooth. 
Eocene to Recent. 
Lobantale, Cossm. Shell compressed, with two internal longitudinal ribs. Eocene. 
Fustiaria, Stol. (Figs. 790, B,C). Shell with a very long and linear ventral cleft posteriorly. 
Cretaceous to Recent. 

Sars, M., Om Siphonodentalium vitreum, en ny Slaegt af Dentalidernes Familie. Universitets- 
Program, Christiana, 1861. 
Stoliczka, F'., Palaeontologia Indica. Cretaceous Fauna of Southern India, vol. II., 1867-68. » 
Gardner, J. S., On the Cretaceous Dentaliidae (Quar. Journ. Geol. Soc. London, vol. XXXIV. pp. 
56-65), 1878. 
Kovalevsky, A., Etude sur Vembryogénie, etc., du Dentale (Ann. Mus. Hist. Nat., Marseille, Zoologie 
Mem. No. I.), 1882-83. 
Plate, L., Ueber den Bau und die Verwandtschafts-Beziehungen der Solenoconchen (Zool. Jahrb., 
Abtheil. fiir Anat. und Ontog., vol. V. pp. 301-386), 1892. [Bibliography, pp. 384-386. ] 
Sumroth, H., Mollusea in Bronn’s Classen und Ordnungen des, Thierreichs, vol. II. pp. 356-467, 
1893-95. 
