150 ROY L. MOODIE 
other lower urodele Amphibia and in the larva of Amblystoma 
are essentially the same as in Acipenser.!8 
In teleostean fishes the area acustico-lateralis, or tuberculum 
acusticum, is much more compact than in ganoids and assumes 
a great variety of forms, in some cases being greatly enlarged. 
The lobes of the two sides may fuse with each other across the 
mid-dorsal plane above the fourth ventricle between the vagal 
lobes and the cerebellum. ‘This is the condition in Gadus.!® In 
Mormyrus the area acustico-lateralis is enormously hypertro- 
phied and takes the form of two dorsal unpaired lobes, a posterior 
one related to the posterior lateral line nerve (vagal root) and 
an. anterior one related to the anterior lateral line nerve (facial 
root). Of these the posterior lobe is the larger and has grown | 
over the anterior lobe so that in cross section the two lobes 
seem to be concentrically arranged, and the whole mass appears 
in surface view as a single unpaired eminence, commonly termed 
the tuberculum impar.°° 
18 Herrick, C. Judson. Thecerebellum of Necturus and other urodele Amphibia. 
Jour. Comp. Neur., vol. 24, 1914, pp. 1-29; The medulla oblongata of larval Am- 
blystoma. Jour. Comp. Neur., vol. 24, 1914, pp. 343-427. 
19 Kappers, C. U. A. The structure of the teleostean and selachian brain. 
Jour. Comp. Neur., vol. 16, no. 1, 1906, plate 6, figs. xcv and xcvt. 
20 Numerous figures of this remarkable teleostean brain have been published, 
amongst others the following: 
Ecker, A. Anatomische Beschreibung des Gehirns vom karpfartigen Nil- 
hecht (Mormyrus cyprinoides L.). Leipzig, 1854. In Ecker’s figures the tuber- 
culum impar is erroneously designated ‘cerebellum.’ 
Sanders, A. Contributions to the anatomy of the central nervous system in 
vertebrate animals. Appendix. On the brain of the Mormyridae. Phil. Trans. 
Roy. Soc. London, Part III, no. 173, 1883, pp. 827-959. In this work the tuber- 
culum impar is erroneously homologized with the lobus facialis of cyprinoids 
(a visceral sensory center which was also called tuberculum impar by the older 
anatomists; see p. 149. 
* 
Smith, G. Elliot. In the catalogue of the physiological series of comparative 
anatomy, Museum Roy. Coll. Surgeons, London, 1902, p. 103, fig. 29. 
Stendell, W. Die Faseranatomie des Mormyridengehirns. Abh. Sencken- 
bergischen Naturf. Gesell., Bd. 36, H. 1, 1914, pp. 1-89. 
Berkelbach van der Sprenkel, H. The central relations of the cranial nerves 
in Silurus glanis and Mormyrus caschive. Jour. Comp. Neur., vol. 25, no. 1, 
1915, figs. 15-19. This paper contains the first accurate and detailed descrip- 
tion of these structures, though Stendell figured and briefly described the true 
relations. 
