Observations upon the Development of the Teleostean Brain. 497 



VI. Explanation of the Plates. 



Plate XXIX, Figs. 1 to 9. 



Fig. 1. Vertical transverse section of anterior extremity of head of 

 1 day old herring. Zeiss A, Oc. 4. Cam. Luc. X ^• 



Fig. 2. A similar section taken somewhat behind fig. 1. Z. A, Oc. 4. 

 Cam Luc. X 2- 



Fig. 3. A similar section taken further back : showing traces of lateral 

 optic ventricles (v. o.). Recess of third ventricle in front of in- 

 fundibulum {r. v. 3.) and last trace of anterior commissure (c. a.). 

 Z. A, Oc. 4. Cam. Luc. 



Fig. 4. A similar section taken through optic commissure of newly 

 hatched herring, showing recess of third ventricle below optic com- 

 missure. 



Fig. 5. A similar section of 1 day old herring taken shortly behind 

 the region of fig. 2: showing olfactory nerve (J), passing to olfac- 

 tory sac (ol.). Z. A, Oc. 4. Cam. Luc. 



Fig. 6. A similar section taken just in front of optic commissure, 

 showing cerebellum (cb.), and dividing commissure (c. d.), shutting 

 off lumen of infundibulum (in.) from third ventricle. Z. A, Oc. 4. 

 Cam. Luc. 



Fig. 7. A similar section taken behind fig. 6, showing ventral com- 

 missure of infundibiilum (c. i), and dice-box {d. h.) and semilunar 

 areas (s. a.) of mid-brain. Z. A, Oc. 4. Cam. Luc. 



Fig. 8. Vertical transverse section through mid-brain of early post-larval 

 herring, showing tori semicirculares {f. s.), and tips of valvula (/". g.). 

 7a. a, Oc. 4. Cam. Luc. 



Fig. 8 a. A similar section taken through optic thalami and pineal body 

 of early post-larval herring. Z. A, Oc. 4. Cam. Luc. 



Fig. 8 b. A similar section taken somewhat behind fig. 8 a. Z. D, 

 Oc. 4. Cam. Luc. 



Fig. 9. Vertical longitudinal section of brain of early post-larval herring. 

 Z. A, Oc. 4. Cam. Luc. 



