1909.] 



OLFACTORY ORGAN OF TELEOSTEAN FISHES. 



617 



are but slightly developed, leaving smooth an appreciable area of 

 the floor of the olfactory chamber around the rosette. 



The relations of the olfactory chamber to the skull are also 

 peculiar (text-fig. 190). It lies above the head of the maxilla, and 

 is thus far in advance of its usual position in the hollow of the 

 ethmoid, although the foramen in which the olfactory bulb lies 

 perforates the lateral ethmoid at the usual spot. An olfactory 

 nerve of unusual length is in consequence interposed between the 

 bulb and the rosette*. 



The abnormal position of the olfactory chamber may be partly 

 explained, as suggested above, by the fact that the tentacle 

 developed in connection with the anterior nostril would be most 

 advantageously placed near the extremity of the snout, but it is 

 also in part due to a shortening of the skull between the orbit 

 and the maxillary process of the palatine. 



Merluccius vulgaris. 



The nostrils occupy much the same position as in the Haddock, 

 but are set quite close together, like those of the Salmonidse, which 

 in fact they closely resemble. The anterior nostril is circular, the 



Text-fig. 191. 



Merluccius vulgaris. 

 Position of olfactory chamber and nasal sac. 



posterior nostril crescentic and embracing the anterior with its con- 

 cavity ; both are wide open. There is no upstanding flap upon the 

 hinder margin of the anterior nostril, but the integument between 

 the two is prolonged into the cavity of the olfactory chamber, 

 forming a curtain (as in the Salmonidse) to conduct water 



• It may be noted that here, and in all other cases observed, the olfactory nerve is 

 very considerably larger than the tract by which the bulb is connected to the brain. 



