38 



A Notice by Thomas Wharton Jones, Esq., was then read, " On 

 the mode of closure of the gill-apertures in the tadpoles of Batrachia." 



Mr. Jones observes, that when the right gill of the tadpole disap- 

 pears, it is not, as is usually supposed, by the closure of the fissure 

 through which it protrudes, but by the extension of the opercular fold 

 on the right side towards that of the left, forming but a single fissure, 

 common to the two branchial cavities, through which the left gill 

 still protrudes. He also remarks that conditions analogous to those 

 which occur during several stages of this process exist in the branchial 

 fissures of the anguilliform genera, Sphagebranchus, 3fonoj)terus, and 

 Si/nbranchus. 



