638 



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



SPHYRiENID^. 



Sphyrcuna cameroonii. 



The nostrils lie in an area of soft skin above the lachrymal 

 bone at a quarter the distance from the eye to the snont. The 

 anterior is a small round hole, the posterior a vertical slit concave 

 posteriorly and valved against ingress by the thinness of its 

 backwardly directed anterior lip. The bridge of skin between 

 the nostrils is rather broader than the posterior nostril is long, 

 the latter being eight times the diameter of the anterior nostril. 



Text-fig. 206. 



\ I a ■•'■■•/.■.■■•'■■•■>-j, -Tr;:rT-- 



J 1 );?^i5pii?^s^ 



SpJit/rana cameroonii. 



A. Position of tlie olfactory organ and nasal sac relative to the bones 



of the face. 



B. Diagram of the olfactory chamber in longitudinal section. 



M., the muscle fragment mentioned in the text. 



The olfactory chamber lies beneath the nostrils and is occupied 

 by a well-defined rosette. Its ventral parts are extended down- 

 wards and forwards under cover of the lachrymal bone to form a 

 long flattened accessory nasal sac, which extends from the ethmo- 

 lachrymal articulation to the anterior end of the lachrymal bone. 



The rosette is of the normal oval type. It consists of about 

 30 strongly convex laminfe (text-fig. 206, B). 



It is difficult to suggest the use of the accessory sac, as the 

 specimen observed was in a fragmentary condition ; but the 

 presence of a piece of muscle and tendon (probably the retractor 

 maxillae) upon the lower border of the lachrymal and underlying 

 the accessory sac, suggests that it may very likely be used as an 

 aspirator bulb, compressed either by the swelling of this muscle 

 or by the upward swing of the maxilla when the mouth is closed. 



