27 



found specimens ; viz. thirteen genera, comprising seventeen 

 species ; many of which are different from the know^n genera 

 of Europe. 



Dr. Gould read a letter, from Dr. Perkins in West Africa, 

 giving an amusing account of his own experience of the 

 difficulties with which Naturalists and collectors have to 

 struggle, in their intercourse with the natives of barbarous 

 countries, in endeavoring by their aid to procure specimens 

 or elicit information. 



Dr. James W. Stone and Mr. John E. Williams were 

 elected members of the Society. 



April 19, 1848. 



The President in the Chair. 



Twenty members present. 



Prof. Agassiz made some remarks on the existence of 

 numerous minute tubes in Fishes, opening externally, which 

 have hitherto been considered mucous tubes, but which he 

 is convinced are tubes for the introduction of water into the 

 body. These openings in some fishes are extremely nume- 

 rous, existing over the whole external surface. In fresh 

 water fishes, and in those living in shallow waters, they are 

 comparatively few. They are most numerous in fishes 

 which swim at great depths. 



In reply to a question of Dr. Wyman, he said that he had not 

 as yet found them in the sharks and rays. These openings are 

 sometimes visible to the naked eye, and sometimes require a 

 magnifying power for their detection. They are very large and 

 numerous, and easily seen, in the head of the common shad. 

 These minute tubes unite into larger ones, in a manner which 

 seems to be the same in each class. He thought this circum- 



