Kingsbury, Oblongata in Fishes, 35 



EXPLANATION OF FIGURES. 

 It is impossible to illustrate this paper adequately since of each form sev- 

 eral figures at different levels would be desirable in order to show the gradual 

 changes undergone in passing from the myel into the oblongata and the appear- 

 ance of the structures discussed in the foregoing. Dorsal views of the oblongata 

 of Amia, Amiurus, Perca and Cyprinus are given. Series of 6 figures of 

 transections of the oblongata in Amia, 5 in Amiurus and two Perca are given 

 to illustrate the modifications, to which are added 8 diagrammatic figures of 

 other forms for comparison. All figures are drawn by the aid of the microscope 

 and camera lucida except figures 2 and 5 and the diagrams of plate V. Figure 

 2 is based upon a photograph. 



Abbreviations. 



ac. — acusticum (system). ni. — motor nidus of the Xth nerve. 



(bl. — cerebellum. p. I. f. — posterior longitudinal fasci- 

 cbl. cr. — cerebellar crest. cuius. 



c. d. — dorsal cornu. sp. V. — spinal (ascending) Vth tract. 



cm. i. — commissura infima Halleri. s. t. tr. — secondary vago-trigeminartract. 



f. c. — fasciculus communis (system). t. i. — tuberculum impar (fused preau- 

 /. /. — lateral line nerve. ditory part of fasciculus communis 



/. t. — lobus trigemini (preauditory por- systems). 



tion of the fasciculus communis). Vllaa. — preauditory fasciculus com- 

 /. V. — lobus vagi (postauditory por- munis root. 



tion of the fasciculus communis), VTIab. — facial proper. 



M. c. — Mauthner cell. Vllb. — acusticum root. 



Mesen. — Mesencephal. Xm. — motor root of the Xth nerve. 



myc. — myelocoele. Xs. — sensory root of the Xth nerve. 



PLATE I. 



Fig. I. Dorsal view of the oblongata of At?tia. The metatela is removed 

 in this and the following aspects since it would interfere with the regions de- 

 sired to be shown. 



Fig. 2. Dorsal aspect of the oblongata of Cyprinus. Metatela removed. 

 The brain cavities were injected with alcohol and the vagal lobes (/. v.) were 

 apparently somewhat spread apart thereby. The cerebellum has been removed 

 and the cut surface only is seen. 



Fig. 3. Lateral aspect of the oblongata of Amia to illustrate the superfi- 

 ciality and course of the spinal V tract to the Vth nerve. 



Fig. 4.. Dorsal aspect of the oblongata of Perca. The cerebellum has 

 ■ been removed and the cut surface alone is seen. 



Fig. £. Dorsal view of the oblongata of Amiurus. 



Fig. 6. A transection through the myel of Amia near the brain. The dor- 

 sal cornua of the cinerea at this level are considerably larger than in a section 

 of typical myel. 



Fig. 7. Transection of the myel of Amiurus. 

 PLATE II. 



Fig. 8. Amiurus. Transection of the myel (oblongata?) near the metatela 

 showing the enormously enlarged dorsal cornua. 



Fig. 9. Amiurus. Transection immediately caudad of the metatela through 

 the beginning of the fasciculus communis system {Cm. i.). The dorsal cornua 

 have diminished slightly in size and the spinal Vth tract has appeared. 



