622 MR, R. H. BURNE ON THE ANATOMY OF THE [May 25, 



behind to form a small valvular flap similar to that of the Gadids 

 and Carps, 



Text-%, 194, 



G-ymnarcJms niloticus. 

 Olfactoi'y organ, from the side. 



Suminiary. 



In the Malacopterygii examined, a distinction can be drawn 

 between the Mormyridfe and the other families. In the former 

 the olfactory organ is of a peculiarly simple type as regards 

 nostrils, cavity and rosette. In the latter (Salmonidte, Clupeidae, 

 Ohirocentridas) there is great uniformity and a relatively high 

 degree of complexity. The nostrils are similar in form, position, 

 and detailed relation to the bones of the circum-orbital ring and 

 are modified, though imperfectly, to direct a current of water 

 through the leaves of the rosette. There is, however (except 

 possibly in Coregonus), no means of confining the inflow to the 

 anterior nostril. The olfactory chamber is extended by an 

 accessory sac with a similar form and position in all the genera 

 examined and directly affected by the movements of the jaws. 

 The laminfe of the rosette though few in number are large and of 

 characteristic claw-like shape. 



ostariophysi, 

 Cyprinid^, 



Tinea vulgaris (text-fig, 195, A), 



The nostrils lie close together near the mid-dorsal line of the 

 face about midway between the eye and the snout. In their 

 general characters they somewhat recall those of the Salmonidae, 

 Both are circular and wide open. The anterior is bordered by a 

 tubular lip, the hinder parts of which, including the whole area 

 between the nostrils, are prolonged upwards to form a projecting 

 hood and also inwards within the olfactory chamber as a curtain 

 that divides this cavity transversely into two. By this combination 

 of an external hood and an internal curtain water would be 



