(588 Dr. IIAKKIS II. WILDER, 



of their original position and have been employed in the service of 

 the nose. This seems a convincing and unexpected proof of the earlier 

 terrestrial life of this animal. 



At an earlier period it must have possessed a well-formed inter- 

 maxillary space furnished with glands which had the usual function 

 of moistening the oral mucous membrane, when the animal changed 

 to a wholly aquatic life, the former function of these glands became 

 superfluous, and they disappeared with the exception of such as, with 

 a change of function could still be advantageous to the animal. The 

 intermaxillary space, not being farther needed, is in process of retro- 

 gression, becoming gradually filled with connective tissue, the lew 

 glandular cells remaining, giving evidence of its former functional 

 development. This view concerning the significance of the nasal 

 glands receives farther support from the fact that similar glands are 

 found in the Axolotl, exactly resembling those of Siren in position 

 and structure. These glands, in a transformed specimen {AmUystoma 

 iveismanni), were found by Wiedersheim to have greatly increased 

 in number, and extended medially until they met and filled the inter- 

 maxillary space. He says: „die beim Axolotl kaum in Spuren vor- 

 handene Glandula intermaxillaris ist bei Amblystoma loeis- 

 manni zu einem stattlichen, das ganze Cavum internasale erfüllenden 

 Organ geworden, dessen physiologische Bedeutung für die Salaman- 

 driden überhaupt ich an anderer Stelle (in: Zeitschr. für wiss. ZooL, 

 Bd. 27) klargelegt habe" (R. conclusions). With regard to the present 

 function of the persisting nasal glands we can only conjecture: 



That they perform some very important service, is evident from 

 their high development, and that this function is peculiar to Swen, 

 is shown by the fact that no trace of such glands is found in the 

 other Perennibranchs. 



Farther investigation of this point seems only possible by physio- 

 logical experiment upon the living animal. 



E. Histology of the nasal mucous membrane. 



Under this head I wish merely to note the histological structures 

 in the different parts of the nasal cavity. As Blaue has supposed, 

 after the analogy of other allied forms, well-developed s m ell- bud s 

 occur throughout the greater extent of its surface. 



Particularly noticeable is this structure in the posterior portion, 

 where the buds lie between the lateral folds, these latter being 

 very thin and serving merely as partitions l)etween the several buds, 



