No. 11. — Bqwrts on the Results of Dredging, under the Supervision 

 o/ Alexander Agassiz, along the Atlantic Coast of the United 

 States, dtiring the Summer of 1880, bi/ the IT. S. Coast Survey 

 Steamer " Blake," Commander J. R. Bartlett, U. S. N., Com- 

 manding. 



(Published by permission of Carlilk P. Patterson, Supt. U. S. Coast and 

 Geodetic Survey.) 



XII. 



Report on the Selachians, hy Samuel Gaeman. 



This notice includes only what were taken during the last cruise of 

 the steamer, with a few shoal-water species previously obtained. No 

 attempt having been made to secure the latter, the collection is small. 

 A single new species and a new variety were found among the captures 

 in depths of less than thirty fathoms. All those coming from great 

 depths appear to belong to species heretofore unknown. The notes 

 secured on the different expeditions, as far as they relate to the Sela- 

 chians, are by themselves insufficient for purposes of generalization. 

 In connection with those taken from the results of other work, on 

 Fishes as well as Selachia, they seem to point toward the following 

 conclusions : — 



First, That the migrations of these animals, including the fishes, are 

 much more limited in extent than has generally been supposed ; and, 



Second, That these creatures are more or less affected by a period of 

 comparative inaction, in a measure corresponding to what obtains among 

 Batrachia and Reptilia, most pronounced, perhaps, in the case of such 

 as the skates. 



Among both Selachians and Fishes there are many species in our waters 

 whose movements do not amount to more than short runs from shoal to 

 deeper water and back again. Others would seem to extend their travels 

 from the coasts and banks to the Gulf Stream. And still others make 

 much more extensive migrations. It is only a question of time and 

 further investigation to enable our fishermen to follow their game with 

 nearly as much certainty as the hunter now follows his, from highlands 



VOL. VIII. — NO. 11. 



