BRANCHIAL SENSE ORGANS OF ICHTHYOPSIDA. 201 



In Triton I have fully convinced myself by actual investigation that 

 Blaue's results are true and accurate. And I have also somewhat 

 examined the state of things in a few fishes. There can really be no 

 doubt as to the accuracy of Blaue's results ; and here it only remains 

 to give a very short resume of the paper, referring the reader who 

 desires further detail to the original, which is illustrated by a number 

 of very beautiful drawings. 



In many Amphibians and fishes the nasal membrane has the struc- 

 ture mentioned above, but in others the indifferent epithelium becomes 

 reduced, so that the bulbs come to lie nearer together. This reduction 

 of the indifferent epithelium begins around the bases of the buds. The 

 basal epithelium is pushed away, and in such a fashion that the bulbs 

 are in contact basally, but are separated distally by indifferent epithe- 

 lium (Exocoetus), 



In Trigia typical smell buds are found along with others that have 

 increased in width and pushed the indifferent epithelium away. 



In Cottus the smell buds are almost completely fused together, but 

 there is still a little indifferent epithelium, and a few buds still remain 

 isolated. 



Lastly, in Fierasfer and others the indifferent epithelium has dis- 

 appeared entirely from the folds of the nasal membrane, and a con- 

 tinuous sensory epithelium is present. 



Thus Blaue has furnished very valuable evidence, from which, in 

 conjunction with our knowledge of the development in Elasmobranchii 

 the nature of the nose can be decided with greater probability than 

 hitherto. 



In Elasmobranchii separate bulbs are not present even in the 

 embryo. The indifferent epithelium has disappeared even in the 

 ontogeny ; but from Blaue's researches on the structure of the nasal 

 membrane in adult fishes generally, and from the mode of development 

 of the nose, its ganglion and nerve, there can really be no hesitation 

 about classing the nose with the branchial sense organs, and hence we 

 are justified in calling it the modified sense organ of a gill-cleft. 1 

 F. E. Schultze 2 had previously stated his conviction that the " Gesch- 

 mackorgane " of taste buds were the last remains of the skin sense 

 bulbs of fishes, and Blaue now homologises the smell buds and the 

 sense bulbs of the skin of fishes. 



1 Beard, "Cranial Ganglia and Segmental Sense Organs," 'Zool. Anz.,' 192, 1885. 



2 F. E. Schultze, " Ueber die becherformigen Organe der Fische," * Zeit. f. wiss. ZooL,' 

 Bd. xii, 1863. 



