DENNIS, ON FOSSIL LIAS. 269 



cumstances, in iletermining about a particular bone or tooth ; 

 that is, try to discover the class and order of animals it most 

 resembles in its general characters. As I have adverted to be- 

 fore, great variety is observed in form and position of the lacunae 

 in the bones of animals ; the canaliculi also vary. Having 

 first of all determined the class, by a strict comparison with 

 known forms, then an attempt should be made to form a 

 judgment of the kind of animal, based upon inductive reason- 

 ing, the result of numerous and accumulated facts ; and 

 unless we study recent bone with this end in view, we shall 

 only half do our work. It is a matter of difficulty, no doubt, 

 and the subject is quite a novel one ; but it affords most 

 interesting material for microscopic inquiry. 



Too great praise cannot be given to Mr. TufFen West for 

 the extraordinary accuracy of his engraving. He says, and 

 truly says, that each lacuna, loith each of its canaliciili, is a 

 study from, nature, and though I see my name at the foot of 

 the Plate, yet I beg to say that all I have had to do with it 

 was in some measure to design its form, and to give Mr. 

 West the sections of bone to engrave from. I left them in 

 his hand to be produced in their truth and perfectness, and 

 most admirably he has accomplished the work. I ought to 

 mention that, for the sake of ready comparison, some fossil 

 and recent sections of bone have been introduced into the 

 Plate. Tliey are as follows: A, single lacuna, with its 

 canaliculi, human ; B, tiger's ; C, boa constrictor's ; D, 

 crocodile's ; E, fossil saurian's, Stonesfield ; F, turtle's, G, 

 conger-eel's : these I term typical. Fig. 19, crocodile, trans- 

 verse section. Fig. 5, Stonesfield, fossil saurian. Fig. 9, 

 fossil vertebra of a whale. Fig. 7, fossil mammal, probably 

 a pahTotherium ; tertiary strata, Touraine. Fig. 20, toad. 

 Fig. 21, fin of sturgeon. Fig. 22, fossil fish, pycnodus, 

 Stonesfield. Fig. 10, fossil mammoth, Till. Fig. 11, ant- 

 eater. Fig. 12, three-toed sloth. Fig. 15, ant-eater, vertical 

 section. Fig. 16, sloth, ditto. Fig. 13, dolphin, ditto. Fig. 

 14, dugong. Fig. 17, dolphin, vertical section. Fig. 18, 

 dugong, ditto. Figs. 1, 2, 2 a, 2 Z>, 3, 4, and 6, representing 

 the fossil in question. 



