180 LETTERS FROM PROF. AGASSIZ. 



In the first place, of fishes: All your representatives of 

 the genera Hydrargyra, Gasterosteus, Lepidosteus and 

 Amia. I have had the last two for a long time under 

 consideration, but having satisfied myself, lately, that 

 Amia is the living representative of all those monsters of 

 the Old Red, which have furnished to Hugh Miller so many 

 puzzles in his Foot2)rints, I should like to finish it up, as 

 well as a review of the Gasterosteus of the United States, 

 which I began when writing the Lake Superior Book. 

 Several new species, found in Florida, have also led me to 

 take up, in the same manner, the Hydrargj-ras, Fundulus, 

 . Lebiar, &c. 



Next, I would beg for your Unios and Anodontas, males 

 and females, in alcohol, if possible in the season preceding 

 the laying of the eggs into the gills, and also with the eggs 

 in the gills, and some dry specimens of all the species of 

 the Lake. 



You may be surprised, but I am not quite satisfied that 

 the Lakes and the rivers emi)tying into them nourish iden- 

 tically the same species as the Ohio. I should be thankful 

 for ampler opportunities of comparing them. 



After all this, permit me to mention also the genus 

 Astacus, of which I have about half a dozen new species 

 from the fresh waters of dilferent parts of the country, 

 which, upon direct comparison, have been found diflerent 

 from those already described. This makes me desirous 

 to compare the Crawfishes from as many localities as pos- 

 sible. 



Do you also collect Lisects? That you observe and 

 study them I see from the Family Visitor- If so, do you 

 want some from this vicinity, and what may I offer you 

 that would be acceptable? II" you will give me a chance 

 to send you something, I would ask lor many other things 

 in which I am not particularly working now, but which I 

 should like to secure for my Museum. 



