The Zoologist — June, 1874. 4013 



In noticing a work by a naturalist so eminent in dentistry as 

 Mr. Bell, I feel great diffidence and greater difficulty in saying a 

 single word about teeth ; but a requirement in Natural History is 

 perpetually forcing itself on my attention whenever a work on 

 sucklers comes before me, and that is the want of a systematized 

 nomenclature of teeth, and a rigid adherence to their homologues 

 and teachings. No one thinks of applying the same name — as 

 cranium, humerus, scapula, pelvis, femur, &c. — to bones in different 

 species of sucklers, unless he believes such bones homologically 

 identical ; but the names of teeth, as incisors, canines, and molars, 

 are used in a conventional, and perhaps convenient, but not in a 

 homologically restricted sense ; the so-called canines of a seal are 

 not the homologues of the so-called canines of a walrus ; the tusk, 

 horn, or tooth of the narwhal, also described as a canine tooth (the 

 left canine) seems a mistake. Would it not be better to consider as 

 homologues all succrescent teeth, or those teeth which through life 

 continue to grow from the basal and at the distal extremity; and 

 also as homologues all those teeth which appear to acquire maturity 

 and become complete in a iew weeks or months. I would make 

 no rule as to the position of succrescent teeth, but seek simply to 

 understand their structure and character; thus the incisors of a rat 

 or rabbit, the horns or horn of a narwhal, the canines of a walrus, 

 and the tusks of an elephant, would come into the same cate- 

 gory of succrescents. I recollect no instance in which so-called 

 canine teeth occur posterior in position or in addition to succrescent 

 teeth, but there are many instances in which complete teeth occur 

 in advance of succrescent teeth : the general rule, however, seems 

 to be that when succrescent teeth are well developed, as in Hydro- 

 potes, Moschus, Elephas, Trichecus, Monodon, &c., no complete 

 teeth precede them. 1 may also remark that when the males of 

 species belonging to tribes usually bearing horns, as the deer, are 

 exceptionally without that armature, they are provided with tusks, 

 and I assume succrescent tusks, as a kind of compensation. 



I cannot expect these crude observations to have much weight, 

 or be received with much favour, but I think it possible they may 

 induce some more competent naturalist than myself to investigate 

 the matter ; if so, my object will be attained. 



In conclusion, I think I have said enough to show that this 

 edition has been issued in an incomplete and unsatisfactory, 

 although I can by no means say in a hasty, manner ; yet there 



SECOND SERIES — VOL. IX. 2 E 



