348 AN INTRODUCTION TO THE STUDY OF FOSSILS 



(Eocene) of Wyoming, and closely related genera are still living 

 in the rivers of New South Wales and Chili. Of the salmons 



Fig. 149. — The caplin, Mallotus villosus Cuvier. (x^.) This member of the 

 smelt family is an abundant fossil in the glacial (Pleistocene) clays of eastern 

 Canada, a.f., anal fin ; c.f., caudal fin (this is homocercal) ; d.f., dorsal fin ; 

 cb., orbit of eye ; pec.f., pectoral fin ; pel.J., pelvic fin. (Redrawn from Logan.) 



(Upper Tertiary to present), fossil skeletons of the existing Mal- 

 lotus villosus are very common in concretions in the Pleistocene 

 clays of Greenland and eastern Canada (Fig. 149). The 

 perches, catfishes, mackerels, codfishes occur from the Eocene 

 to the present, eels since the Cretaceous and pikes since the 

 Miocene. 



1. Give distinguishing characters of Class Pisces. 



2. How do the majority of fish breathe ? the lung-fish ? 



3. State briefly the probable origin of the fins; the three 

 kinds of caudal fin. 



4. What distinguishes the sub-class Elasmobranchii ? 



5. Give its geologic range. 



6. Name some living examples of this sub-class. Name 

 some fossil examples. 



7. Sketch a tooth of Lamna or Carcharodon, both broad 

 and narrow views. 



8. Give geologic range of the sub-class Holocephali; a 

 living example. 



9. Define the sub-class Dipneusti, noting the significance of 

 the name. 



10. Give its geologic range ; fossil and living representatives. 



11. Give geologic range of the sub-class Teleostomi. 



12. Into what four orders is this sub-class divided? Give 

 fossil and living example of each. 



