Volume I. December, l8gj. Number 



ZOOLOGICAL BULLETIN. 



THE AMPULLAE OF LORENZINI OF THE 



SELACHII. 



JAMES E. PEABODY. 



I SHALL give in this paper an abstract of some of my results 

 obtained from work on the smooth dogfish (Galeus cam's, 

 Mitchill), reserving the plates and a fuller description of the 

 lateral-line system, ampullary organs, and Savi's vesicles (of 

 Torpedo) for a more extended paper. 



The most casual observation of any of the elasmobranch 

 fishes shows the presence of a large number of pores opening 

 upon the surface. When the skin is pressed a thick, gelati- 

 nous, transparent substance is seen to ooze from them, which 

 on mixing with the water covers the surface of the fish with 

 slime. A closer observation and a careful dissection is neces- 

 sary to establish the fact that these pores must be classed in 

 two distinct groups : to the one group belong the pores of the 

 lateral-line system, and to the other the pores of the ampul- 

 lary tubes. It is well-nigh impossible in many genera to dis- 

 tinguish superficially the one class of openings from the other. 



In tracing the course of the lateral-line canals I have em- 

 ployed the following method. The canals were cleared from 

 their mucous contents by forcing ether through them by means 

 of a syringe and fine canula. When the ether had made its 

 way through all the canals and tubules, an injection mass com- 



