9 8 



CHAPTERS ON EVOLUTION. 



and in no less degree by supplying the theoretical connection required 

 to connect detached facts with the main body of scientific knowledge. 

 A popular excursion into the domain of comparative anatomy 

 will present us with several apt illustrations of these remarks, and 

 will serve to prove the truth of the assertion regarding the import to 

 science at large of the veriest " odds and ends " in natural-history 

 trifles. Of such " ends," in one sense, the tails of fishes may be said 

 to present us with examples of the most literal kind. The class of 

 fishes unquestionably presents an interesting field of inquiry to zoology 

 of the most popular nature. There might possibly exist, however, a 

 shade of hesitation on the part of even enthusiastic students of fish- 

 lore, in affirming the truth of the assertion that in the tails of fishes 

 we may perchance find a study of more than usual interest. These 

 structures are unquestionably elegant enough in their way, and, 

 whether as constituting the propelling agents or the steering-gear of 

 their possessors, claim a just share of zoological attention. But that 

 on the caudal appendages of fishes we may presume to " hang a tale " 



of the probable origin 

 and evolution of the 

 race at large, is an ex- 

 pectation by no means 

 warranted on a brief 

 review and considera- 

 tion of the apparently 

 trivial nature of the 

 subject. In the history 

 of scientific speculation, 

 however, " tails " have 

 played more than one 

 prominent part. On 

 more than one occa- 

 sion a theory of tails 

 has been gravely dis- 

 cussed, and hotly de- 

 bated ; and it is indeed 

 difficult to assign a 

 reason why the appa- 

 rent insignificance of 

 the subject should dis- 

 guise and conceal its 

 real importance. Possibly owing to the deterioration of the caudal 

 region in the human subject, the importance of the " tail " in lower life 

 acquires thus a tendency to become thoroughly overlooked. Were a 

 spider monkey (Fig. 35), however, capable of forming and expressing an 

 adequate opinion on the value of his tail, consisting, as it does, of some 



FIG. 35. SPIDER MONKEY. 



