348 



Bashford Dean Memorial Volume 



Text-figure 15. Text-figure 16. 



Teeth of two fossil Chlamydoselachids from the Tertiary. 



Text-figure 15. Fossil teeth of Chhmydoselachus lawkyi from the Pliocene of Orciano, 

 Tuscany, Italy. Note the lack of rudimentary cusps. 



1 and lb, teeth viewed from above; la, from below; Ic, from the side (lb, natmral size; all others x 2). 

 After Lawley, 1876, Figs. 1 to Ic, pi I. 



Text-figure 16. A fossil tooth (A, natural size; B, x 2) of Chlamydosehchus tobleri from 



Trinidad, British West Indies. Note presence of rudimentary cusps. 



After Leriche, 1929. 



of phylogenetic deductions based on a comparison of present'day fishes with fossil forms 

 that are known only by their teeth. 



In the fossil Chlamydoselachus lawleyi (Lawley, 1876), which is known only by 

 its teeth (Text-figure 15), the resemblance to the teeth of C. angumeus is very close. 

 Apart from their smaller si2;e, the teeth of C. lawleyi differ from those of C. anguineus 

 only in that they lack the pair of very small cusps. In C. tohleri, which is known only 

 from a single fossil tooth (Leriche, 1929), the small cusps are present, but in some other 

 respects the tooth (Text-figure 16) is so different that one may regard the inclusion of 

 this form in the genus Chlamydoselachus as merely tentative. 



Text-figure 17. Text-figure 18. Text-figure 19. Text-figure 20. 



Teeth somewhat resembHng those of Chhmydoselachus anguineus, from various fossil sharks. 



Text-figure 17. Tooth (x 5) of Cladoselache fyleri from the Devonian. 



After Dean, 1909, Fig. 5. 

 Text-figure 18. Tooth of Cladodus acutus from the upper Devonian. 



After Agassiz, 1843. 



Text-figure 19. Tooth of Ctenacanthus clar}^ from the Carboniferous. 



After Dean, 1909, Fig. 42. 



Text-figure 20. Tooth of Hybodus reticuhtus from the lower Jurassic. 



After Zittel, 1923, Fig. 93. 



