138 ANNALS NEW YORK ACADEMY OF SCIENCES 



time, of the jaw muscles in some of the common vertebrates ; he also made 

 some observations on the mechanics of the jaw action. He studied the 

 following forms: Dog, horse, sheep, porpoise, bird, Crotalus durissus, 

 alligator, frog, pike and whiting. He failed to differentiate many of the 

 muscles and made no mention of innervation, which is one of the chief 

 criteria used at the present time. The names applied were based upon 

 the origin and insertion of the muscles. He applied this principle to the 

 different classes and gave the muscles names. He did not attempt homol- 

 ogies, except as based upon similar function. He misinterpreted the 

 detrahens mandibulae of Ornithorhynchus, as all the others had done until 

 the neurology was worked out by later workers. 



The greatest stimulation to the work was given by the researches of 

 Ruge on the facialis nerve. He studied this throughout the vertebrates 

 from the elasmobranchs to mammals and gave a reliable basis for the 

 determination of the muscles of this group. Schulman, in his work on 

 the trigeminus musculature of the monotremes, cleared up some of the 

 puzzles that this aberrant group present. Lubosch, Fiirbringer and others 

 have added much to this work, so that the comparative anatomist now 

 has extensive material for comparison. Gaupp in his work on Eeichert's 

 theory of the origin of the auditory ossicles and Versluys in his studies 

 on the auditory organs in reptiles have worked in this rich field and have 

 given the material a definite meaning, especially in some of the trouble- 

 some problems relating to the changes that took place in the shifting of 

 the bones and muscles, when reptiles of some sort were changed into 

 mammals. 



Many other investigations have given much information on the muscu- 

 lature of special forms of vertebrates. Chaine, Rouviere, Bijvoet, Toldt, 

 Parsons and others have collected the necessary data on the digastric 

 muscle and have given very full accounts of the condition of this muscle 

 in the mammals. Toldt, in his paper on the jaw articulation and its 

 problems, gives us a basis for the classification of the types of vertebrate 

 jaws, of their articulations and of the correlated types of musculature. 

 Apparently the present work is the first to give a general illustrated re- 

 view of the jaw muscles of vertebrates and to apply this knowledge to an 

 interpretation of the skull structure of recent and fossil types. 



The study of 26 different forms, representing the classes Pisces, Am- 

 phibia, Reptilia, Aves and Mammalia, has demonstrated that the muscle 

 masses in general are severally homologous from the Pisces to Mammalia, 

 and that they may be grouped into two great systems : First, the muscles 

 innervated by the ramus mandibulars trigemini V 3 , and, second, the 

 muscles innervated by the facial nerve (VII). There is a sharp line 



