642 MB. R. H. BURNE ON THE ANATOMY OF THE [May 25, 



The rosette which covers the floor of the olfactory chamber is 

 sharply defined and very prominent, like that of the Perch. It is 

 composed of about thirty claw-shaped transversely pleated laminfe 

 arranged in the usual way radially around the hinder parts of a 

 linear raphe. 



The whole of the olfactory chamber above the rosette is dilated 

 to form a peculiai-ly capacious ethmoid accessory sac, that extends 

 backwards into two hollows beneath the anterior end of the 

 frontal, inwards between the backward process of the premaxilla 

 and the mesethmoid, and forwards between the palato-premaxillary 

 and ethmo-maxillary ligaments and the greatly elongated head of 

 the maxilla. 



In a similar way the wall of the olfactory chamber below the 

 hinder end of the rosette is expanded beneath the lachrymal bone, 

 forming a pear-shaped lachrymal nasal sac that rests partly on 

 the palatine and partly upon the buccal membrane between its 

 anterior border and the maxilla. 



The hinder part of the olfactory chamber is also produced 

 backwards beyond the posterior nostril to form a narrow conical 

 sac above the eye within the hollow between the lower edge of 

 the frontal and the lateral ethmoid. The resemblance should be 

 noticed between this posterior extension and that seen in the 

 Salmons and Herrings. 



The ethmoid and lachrymal sacs are strongly compressed by 

 the movements of the premaxilla and maxilla when the mouth is 

 closed. 



MULLID^. 



Mullus harhatus. 



The nostrils are inconspicuous, but occu^Dy a similar position 

 upon the face to those of the previously desciibed Perciformes, 

 although separated by a considerably broader bridge of skin. The 

 distance between them is due in large part to a tubular extension 

 of the nose-cavity between the olfactory chamber and the posterior 

 nostril. The anterior nostril is a small round hole, the posterior 

 a narrow vertical slit, opening backwards and valved against 

 ingi"ess by the thinness and flexibility of its backwardly directed 

 anterior lip. 



The olfactory chamber is expanded above and below the olfac- 

 tory rosette to form a pair of accessory sacs similar to those of the 

 Perch, but longer and more slender and separated more definitely 

 from the olfactory chamber itself. Although occupying the 

 normal positions between the premaxilla and ethmoid and near 

 the hinder border of the maxilla, these sacs, owing probably to 

 their small capacity, do not seem to be greatly compi-essed by the 

 movements of these bones — at least, no air-biibbles could be driven 

 from the nostrils by forcibly closing the mouth under water. 



The rosette, as in the other Perciformes, is oval and veiy 

 prominent. The laminae are few in number and, like those of the 

 Perch, have a sharply convex free border. 



