384 Harris Hawthorne Wilder, 



chiridium is seen to continue, since of the few living representatives 

 of the group, every one has suffered some modification of the free 

 limbs, usnally in the form of reduction. Thus Proteus and Amphiuma 

 have, in some cases two, in others three digits; Siren has lost the 

 posterior limbs entirely, and Nectunis has but four digits on each 

 foot, instead of five, generally supposed to be the typical number. 

 Cryptobranchus , long the favorite of the investigator because of 

 its large size and the usnal pentadactylons condition of the hind 

 feet, is naturally higher than any Perennibranch and may not be 

 supposed to show a much more primitive condition than one of the 

 higher Salamanders. 



Onr best choice would thus seem to be Nechirus, in spite of the 

 apparent loss of a digit, since this animal would presumably show 

 more primitive relationships than would any Derotreme, and in the 

 number of its toes more nearly approaches the number assumed to 

 be the normal one than any other Perennibranch. In addition to 

 this, the exact correspondence of the two free limbs in the matter 

 of skeleton leads one to hope that this correspondence may extend 

 also to the other parts, the muscles especially, and thus furnish the 

 ground upon which a scientific serial homology may be based. 



It is with these points of theoretical importance in mind that 

 the investigation here presented was undertaken, and it is hoped 

 that the written and pictured description of this, our earliest avail- 

 able tetrapod, may be of value in many questions of comparative 

 myology. One thing becomes at least clear, and that is, the cum- 

 bersomeness of our present nomenclature in giving two distinct 

 names to parts clearly the same, as in the case of the majority of 

 the muscles of the free Limb. That the most of these differences, 

 like Humero-metacarpalis vs. Femoro-metatarsalis, or Extensor ra- 

 dialis vs. Extensor tibialis, are due to a keeping up of the double 

 nomenclature of the skeletal parts strengthens the appeal for a 

 rationalizing of the terms, at least upon such safe grounds as carpus 

 and tarsus, where the homology is sure. 



The difficulties of our present nomenclature are constantly 

 apparent, and in cases where the two limbs are compared the re- 

 sults are often extremely cumbersome. As an illustration of the 

 present necessary mode of expression where comparisons of this 

 nature are dealt with I may cite the opening sentence from a paper 

 on the arteries of the hand and foot (Baum, in: Anat. Anz., Vol. 31, 

 p. 428), in which the result is wholly the fault of the nomenclature, 



