Brigham.] 126 [February 15, 



and also that our classifications are to be drawn from the mature 

 characteristics and not from embryology alone, which would, if taken 

 by itself, throw the study of all low forms into confusion. 



In conclusion I would say, that, while adhering to the views enter- 

 tained by the most eminent naturalists of the present day, I am by 

 no means unwilling to modify my opinions when good cause is shown ; 

 but I cannot dp so on vague and unproved statements, doubtful 

 homologies, or supposed identity of trivial points of structure. 



I look forward ; as others do, to the publication of Mr. Morse's re- 

 searches, with the greatest interest; and trust that the essential 

 points of my arguments, which he has not attempted so far to refute 

 or even to allude to, will be met with all the facts in his possession. 



Truth will infallibly be established through such discussion, which 

 is the final aim of all, and which will endure after the discussions are 

 forgotten. While Allinan, who has made a life-long study of the 

 Polyzoa, finds the most intimate homologies between them and the 

 Lamellibranchs, and Kovalevsky and Hajckel show the strongest em- 

 bryological affinity between the Tunicates and Vertebrates, we may 

 well pause in our speculations and more profitably devote ourselves 

 to active research. Facts brought forward are immutable, while hy- 

 potheses and inferences depend on the individual observer, and in 

 many cases have the most fleeting duration. 



Mr. Wm. T. Brigham described the system of volcanoes in 

 Mexico, which he said was arranged in a line between the 

 West Indies and Hawaiian Islands. He referred to the geo- 

 graphical position of Orizaba, near Vera Cruz, which has re- 

 cently been active. The first eruption took place in 1456-7. 

 In 1569, another occurred, throwing up immense columns of 

 ashes and boulders, which now resemble those that have been 

 subjected to glacial action. It has since been quiet until last 

 year, when it was again active, causing much destruction. 

 In March, 1870, Ceborujo was in a state of activity. He 

 read an interesting account of this eruption, showing its ef- 

 fects upon the magnetic needle. He next referred to the 

 well known volcano Jorulto. In reply to a question from Dr. 

 C. T. Jackson, he said that fishes six or eight inches in length 

 had been taken from subterranean lakes in the vicinity of 



