. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 27G ANATOMY OF VERTEBRATES. 179 there are no lateral lobes in the cerebellum in Fishes, these crura are rudimentary, and the ' pons' is absent. In the Shark they connect the sides of tlie liase of the cerebellum with the ' restiform commissure,' figs. 172 & 187, I. In most Fishes two fasciculi of medullary fibres proceed, as ' anterior crura,' from the under and fore part of the cerebellum, or converge from the lateral and fore- part forward, to form the inner wall or septum, fig. 184, r, of the optic lobes: these an
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 27G ANATOMY OF VERTEBRATES. 179 there are no lateral lobes in the cerebellum in Fishes, these crura are rudimentary, and the ' pons' is absent. In the Shark they connect the sides of tlie liase of the cerebellum with the ' restiform commissure,' figs. 172 & 187, I. In most Fishes two fasciculi of medullary fibres proceed, as ' anterior crura,' from the under and fore part of the cerebellum, or converge from the lateral and fore- part forward, to form the inner wall or septum, fig. 184, r, of the optic lobes: these answer to the ' processus ii cerebello ad testes ' of the himiau brain: tliey are connected below their origin at the under part of the ccreljellum by one or two trans%'erse fasciculi of white fibres, forming the ' commissura ansulata,' which crosses the pre-pyramids just behind the ' hypoaria,' fig. 185, n. The inferior white surface of the cerebellum, which forms the roof of the fourth ventricle, is called ' discus cerebelli,' and from this part small tuljer- cles project in a few fishes (e. g. Blennius and Sturio, fig. 173, c). The restiform columns, quitting the post-pyramidal crura of the ccreliellum, and liaving elfected hj their previous confluence therewith some interchange of filaments, swell out at the anterior lateral parts of the medulla oblontrata, and cive orifrin to the ajreat trio-eminal nerve. They here form considerable 'trigeminal lobes' in the Loach and Herring, fig. 184, /, and are folded or'fimbriate'in C/H'mffir«,fig. 179, dd, and most Plagiostomes, where they are closely connected with a thick vascular mass of pia mater and arachnoid. The trigeminal lobes are convolute in the Skate; enormous and blended with the vagal lobes in the Torpedo ; but in most Osseous Fishes (Lepidosteus, Cod) they are not developed so as to merit tlie name of lobes. In the Cod the inner surfaces of the restiform bodies project into the fourth ventricle, and obliterate the fore p
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