NATURAL SCIENCES OF PHILADELPHIA. 259 



and got on very well in his preserves till about the ISth of Febru- 

 ary, when he found that tliey eon id not be preserved in the small 

 space at liis disposal for them and they began to die from confine- 

 ment. 



I had previously arranged with Mr. Baird that these fish should 

 be deposited in the Susquehanna a gift from the Government to 

 I'ennsylvania so Dr. Slack said I must get ready as soon as 

 possible, as he feared the mortality amongst them might spread. 

 The weather was so warm that we could not move them until the 

 3d inst. as stated by which time the loss had reached to one 

 hundred and tit'ty individuals. The3'- were transported across 

 from Xew Jersey, about seven miles from Easton, to Harrisburg 

 on the day named, and I had them placed in the water in an air 

 hole in the ice close to the shore at Harrisburg about one hun- 

 dred died on the passage about fifty were much weakened bj^the 

 journe}' but recovered in a few minutes after reaching the new 

 water. I>ut the balance, the healtliy ones, immediately made for 

 the current, and disappeared under the ice with as mnch energy 

 as if they were native to our Susquehanna. 



The water, when they entered, was 36 Fahr. at the time, but 

 the river bottom is full of springs at whicli they could warm them- 

 selves. Had I the least idea that there was no description of 

 them, I should have noted their peculiarities in my unscientific 

 way more particularly, but as it is the above is the best descrip- 

 tion T can give you of them. Dr. Slack, I believe, fed them after 

 they had parted witli their 3'olk sack ; but I concluded, from my 

 own judgment, that the best thing I could do was to trust them to 

 the magnificent Susquehanna. The energy with which the healthy 

 ones put out leads me to hope that they will live if not devoured 

 by enemies ; but should they die we can rejieat the experiment 

 with a larger quantity hereafter. 



Your obedient servant, 



JAMES WORR ALL. 



Prof. E. D. Cope, 



Philadelphia. 



April 15. 



The President, Dr. Ruschenberger, in the chair. 



Twenty-five members present. 



The following paper was presented for publication : 

 "Observations on a change of Structure of a Larva of Dryo- 

 campa Imperialis." By Thos. G. Gentry. 



RemarJcH on Extinct Mammah from Califoy^nia. Prof. Leidy 

 directed attention to some fossils, which he had borrowed, through 



