86 OSBORN. [VoL. II: 
consisting of small cells such as Ahlborn describes (see Fig. 
19). His upper 8th nucleus, VIII., corresponds exactly with 
my lower 7th nucleus, 7 #z, this agreement raises a question 
whether Ahlborn’s upper 8th root does not pass into the 7th 
nerve. If such is the case, the homology with Cryptobranchus 
is remarkably close. 
In the upper portion of the encephalon in Petromyzon is 
found the posterior longitudinal fasciculus, approaching 
the Oculo-motor nucleus, and according to Ahlborn, not termi- 
nating with it, but decussating at this point to enter the thalami 
(p. 274). The descent of Meynert’s bundle to the inter- 
peduncular ganglion is also seen The taenia thalami 
optici, p. 285, with fibres entering both the hemispheres and 
the thalami, is homologous with the superior commissure. 
LITERATURE. 
AHLBORN. Untersuchungen iiber das Gehirn der Petromyzonten. Zeit. f. wiss. Zodl., 
1883, p. 192. 
BELLONCI. Sulle Commissure Cerebrali Anteriori degli Anfibia e dei Rettili. Bologna, 
1887. Mem. del. Real. Accad. del. Sci. dell. Istituto di Bologna. Ser. IV., 
Tom. VIII. : 
Intorno alla struttura e alle connessioni dei lobi olfattorii negli Artropodi 
superiori e nei vertebrati. — Atti della R. Acc. dei Lincei, 1881-82. 
EDINGER. Zehn Vorlesungen iiber den Bau der Nervésen Central-organe. Leipzig 
1885. 
Ueber die Verbindung der sensiblen Nerven mit dem Zwischenhirn. Ana- 
tomischer Anzeiger. 1887. 
FISCHER. Anatomische Abhandlungen iiber die Perennibranchiaten und Derotre- 
men. Hamburg, 1864. 
FULLIQUET. Recherches sur le Cerveau du Protopterus Annectens. Genéve. 1886. 
GASKELL. Journ. of Phys., 1886, Vol. VII., p. 1. 
GEGENBAUR. Die Metamerie des Kopfes und die Wirbeltheorie des Kopfskeletes. 
Morpholog. Jahr. Band XIII., pp. 1-112. 
HILL. The Grouping of the Cranial Nerves. Brain, Part XXXIX., 1887. 
KOpreEN. Zur Anatomie des Froschgehirns. Arch. f. Anat. u. Phys., Anat. Abth., 
1888, pp. I-32. 
Orr. The Embryology of the Lizard. Journ. of Morphology, Vol. I., No. 2, Decem- 
ber, 1887. 
OsBoRN. Preliminary Observations upon the Brain of Amfphiuma. Proc. Phila. 
Acad., 1883, p. 177. Preliminary Observations upon the Brain of A/enopoma 
and Rana. Proc. Phila. Acad., 1884, p. 262. 
The origin of the Corpus Callosum, etc. Morph. Jahrb., Band XII., 1886. 
Part I., p. 223; Part IL., p. 530. 
1 Ahlborn has followed this bundle, asymmetrical in Pe¢romyzon, into the medulla. 
