Kingsbury, Oblongata in Fishes. il 



and birds the cerebellum consists of a cortex of well defined and 

 characteristic structure and an ental mass of fibers. In reptiles 

 the last seems to be wanting or ill-defined and the granular 

 layer of the cinerea ( cortex ) becomes more closely applied to 

 the endyma. Among the Ichthyopsida the simplest condition 

 of the cerebellum exists in Urodeles, Petromyzon ( Marsipo- 

 branchs?) and Protoptenis ( Dipnoans?) where it is represented 

 by a bridge over the cavity cephalad of the metatela, composed 

 of fibers passing from one side to the other, and an associated 

 and sometimes insignificant layer of apparently indifferent nerve 

 cells. In presumably all the remaining classes, at least in 

 Ganoids, Teleosts and Elasmobranchs ( Rohon 'yj, Viault 'y6, 

 Sanders '86) the cerebellum presents the structure typical of 

 the cerebellar cortex in higher forms, namely, an ental granular 

 mass or layer and an ectal molecular layer of fine fibers, and 

 between them a more or less well defined zone of large cells 

 sending their dendrites into the molecular layer, — undoubted 

 Purkinje cells. In all these ( as far as examined ) the molecu- 

 lar layer extends caudad over the oblongata, and in Ganoids and 

 Teleosts so far as investigated, it is associated only with the portion 

 serving as the center for the acustic ajid lateral line system of 

 nerves, the Acusticum. This is an important relation that 

 should be emphasized. In some forms at least, (e.g. Amiiirus 

 et. al. Fig. ii.) the layer of Purkinje cells also extends caudad 

 upon the oblongata. In sharks and rays the molecular layer 

 extends almost to the caudal limit of the metatela covering in 

 part the so-called Lobi trigemini ^ and the corpora restifonnia 

 which also possess the granular and Purkinje cell layers. 



Ascertainment of its exact relations in the oblongata of 



i"Im innigen Zusammenhange mit den Lobi trigemini stehen aucb die 

 Corpora restiformia welche gleichfalls nur eine directe Fortsetzung der oberen 

 durcheinander gewundenen Hinterhirnsubstanz vorstellen. Anfangs bestehen 

 die Corpora restiformia aus der Grundsubstanz oder Neuroglia [molecular layer] 

 und den Antheilen der inneren Hinterhirnmassen, spater aber bleibt von ihnen 

 nur die Neuroglia zuriick, welche sich als ein Mantel auf den oberen Seiten- 

 massen des Nachhirnes, die Pedunculi cerebelli bedeckend, bis in die Hin- 

 terstrange des Riickenmarks erstreckt, wo sie die Substantia gelatinosa Rolando 

 2um grossten Theile darstellt." Rohon, p. 84. 



