Terry — The Nasal Skeleton of Amblystoma punctatam. 97 



statemeat regarding the anatomy of the olfactory bulb, nerve 

 and nasal sac. 



The caudal limit of the olfactory bulb in young lar- 

 vae of Amblystoma is indicated on the surface by a 

 slight groove on the lateral aspect of the cephalic end of 

 the brain (Fig. 2, Olf.). Stieda ('75) describes a limiting 

 furrow for the Tuberculum olfactorium in Axolotl ; Gaupp 

 ('99) has shown one to be present in Rana; and Kingsbury 

 ('95) finds the area of olfactory glomerules inNecturus out- 

 lined by a furrow, better marked on the lateral surface of the 

 brain. Corresponding closely to the position of this groove 

 is the limit of the terminations of the olfactory nerve fibers 

 which make a conspicuous field in the sections ; the glomeru- 

 lary arrangement itself , however, is hardly discernible. The 

 direction of the olfactory nerve is laterad in the younger ani- 

 mals in conformity with the position of the nasal sac. This is 

 at first lateral of the brain and projects further ventrad, while 

 the cephalic extremities of the two organs reach about the 

 same level. These relations are considerably changed while 

 the animals are still very small. The nasal sac presents 

 thick walls except laterally where the narrow lumen lies 

 near the surface. The general cavity of the nose in the 

 younger animals is a simple tunnel running between the exter- 

 nal and internal nares. Midway between these openings is the 

 mouth of a diverticulum from the main nasal sac, the Jacob- 

 son's organ of Bawden's account (J. O. in the figures). 

 The position of Jacobson's organ in young larvae is at the 

 ventral side of the main-sac ; in older ones lateral and be- 

 neath it. This organ presents a small surface toward the 

 median plane where the duct of Jacobson's gland opens. 

 The latter lies between the ventral wall of the main 

 nasal sac and the floor of the nasal capsule, extending mesad 

 to the olfactory foramen. In older animals a small protru- 

 sion from the side of the general cavity near its cephalic end 

 receives the nasolacrimal duct (Fig. 4, N. L. P.). 



Winslow's stage III. is a larva of 12mm. in which the 

 trabeculae terminate in the plates known as Cornua and pres- 

 ent crests which have grown dorsally serving in this and 



