NERVOUS SYSTEM OF REPTILES AND BATRACHIANS. 81
I would suggest, however, to those who may feel disposed to regard these cells as connected with the sense of hearing, that such a view involves giving to this apparatus, in its central portion, a structure almost identical with one universally admitted to be motor, like, for example, that concerned in raising the lower jaw; whereas in the central structures for vision and olfaction the cells are all very small.
Moreover, these large cells, found in the vicinity of the acoustic nerve in some lizards, turtles and serpents, are not found at all in the frog, while in the alligator their position indicates that they may be related to the motor branch of the fifth pair or possibly to the branch which supplies the depressor muscles of the lower jaw. The eminentia acoustica in the latter animal swarms with uniformly small cells and nuclei which are very probably the sole centres for the acoustic nerve, and in the same relative plane the same numerous groups of small cells can be seen in frogs and some lizards.
During the past summer, through the kindness of Prof. S. F. Baird, of the Smithsonian Institution, quite a number of valuable specimens have been placed at my disposal, among which may be mentioned Heloderma Suspectum, several serpents and one large example of Chelydra Serpentina.
Nuclei of the cells of the inferior (anterior) horns of the caudal, lumbar, dorsal, cervical and upper cervical regions of the spinal cord, in a large number of frogs of three species, two species of emys and two of land turtles, and in several alligators and lizards, including heloderma, have been measured. Of those found in the cervical and lumbar enlargements enough has been written already in the two preceding papers. The preponderance in average size is here in striking accord with that of the power of the
