Agassiz.] Oo4 [Januarys, 



accepted. The renewed and successful solution of this ques- 

 tion, Prof. Agassiz considered due to many persons, but most 

 especially to the author of the valuable paper just read. 

 Mr. Perry had personally collected the fossils, studied the 

 rocks, and furnished all geologists with the materials used in 

 the discussion of this topic. 



Professor Agassiz stated that he had recently been review- 

 ing the Siluroid fishes for the sake of illustratnig the defini- 

 tions he had long since presented for the different categories 

 of structures among animals. 



The Siluroids had always been considered a natural group ; placed, 

 iit finst, in. a single genus which was subseipiently divided into two, 

 they were next considered a family including several genera, and 

 finally an order, embracing several groups termed fomilies. Was 

 tlierti then no meaning in the terms genus, family, order V Professor 

 Agassiz urged strongly that the application of these terms should be 

 iinilbrm, since a genus really remains a genus no matter how numerous 

 its subdivisions. He believed that orders Avere founded vipon degrees of 

 complication of structure, and families upon the forms of animals. 



Gill, finding that Bleeker had divided the group of Siiuroids into 

 several families, raised it one grade higher and called it the order 

 of Nematognathi — a name implying a structural feature of no ordinal 

 value whatever. Professor Agassiz claimed that the group was an 

 order of Ganoid fishes which shouhl be placed between the sturgeons 

 and garpikes ; thej' had one striking feature in the structure of the 

 jaws, not only reptilian, but bird-like ; this was the power of sliding 

 the palatine bone upon the sphenoid and thus thrusting the barbel 

 forward. The brain greatly resembled that of a sturgeon. Four 

 families were mentioned belonging to the order, the Goniodonts, the 

 LoricariaB, the CalHchthyoids and the Doradides ; their characteristic 

 forms, arising from the peculiar development of the parts about the 

 lateral line, were represented on the blackboard. 



January 3, 1868. 



The President in the chair. Forty-six members present. 



The following gentlemen were elected Resident Members : 

 Rev. Louis B. Schwartz, Dr. B. L. Delano and Messrs. 

 George G. Lowell, Percival L. Evei-ett, .Joseph Pratt, Arthur 



