. BI0GRAP[IIC7^L SKETCH OF ISAAC LEA, LL. D. LIII 



Of embryonic forms of Unionidce tbere are thirty-eight species de- 

 scribed and fignred. Of soft parts of the Unioniclw there are two hun- 

 dred and fifty-four different species, and these are preserved in thirty- 

 four large gkiss jars in alcohol. In the thirteen volumes quarto there 

 are two hundred and eighty plates. 



A few letters and extracts of the many received from his correspond- 

 ents may prove interesting in connection with his work referred to in 

 them: 



New Haven, Becemher 21, 1860. 



My Dear Sir: Your very kind recollection of an old friend is gratefully acknowl- 

 edged. 



lu addition to numerous favors of an earlier date, I have now to thank you for 

 your beautiful coutinuatiou of the descrijitiou and figures of the Unionida; of the 

 United States and Northern Mexico, Vol. 8, Part I, with IG plates. The figures are 

 very beautiful, "and no doubt exact as beautiful. 



Your intelligent perseverance with consummate skill aud taste have reared a bril- 

 liant monument in this part of conchology, not to mention your always valuable 

 memoirs on other topics. 



With every good wish, and a grateful sense of your unremitting kindness to me, 

 I remain, my dear sir, with much esteem and kind regard, 

 Y''our obliged friend and servant, 



B. SILLIMAN. 



To Isaac Lea, Esq. 



[Extract from Silliman's Journal.] 



" Mr. Say still continues to devote his attention to the Uniones, as appears from the 

 numbers of the American Conchology published at New Harmony. Dr. Hildreth, of 

 Marietta, has also contributed his share toward the elucidation of the Ka'iades. But 

 the papers of Mr. Isaac Lea, in the Transactions of the American Philosophical So- 

 ciety, stand pre-eminent among all the labors of this kind, both for extent and nicety 

 of discrimination. This gentleman has explored, in person, their localities, and has 

 had the good fortune to receive, from time to time, the most abundant supplies of 

 them from his friends resident at the West, so that his cabinet, as all can testify who 

 have exau)ined it, illustrates the different species in a high degree of completeness, 

 containing individuals of all ages, and from distant localities, and those which ex- 

 hil)it also the various accidents under which they are liable to occur. Nor have his 

 examinations been confined to the mere shells and dead animals ; he has preserved 

 the same individuals alive under his eye for months, and the observations he records 

 concerning their habits and anatomy are extremely interesting- and original." 



British Museum, London, March 7, 1861. 

 Dear Dr. Lea : I have been favored by a copy of the first part of your eighth vol- 

 ume of the work embodyiTig your life-long labors on the Unlonidw, and return you 

 many thanks for that and its predecessors. You have set a noble example of jjer- 

 severing devotion to the elucidation, and making known to your fellow-men, of the 

 portion of God's creation selected by jour judgment, taste, and opportunities for 

 your studies. You will leave a grand and enduring monument of what one man may 

 accomplish under such conditions, and I trust you, may enjoy many years cheered by 

 th(^ retrospect of past labors, and by the grateful estimation in which they are held 

 by the naturalists and lovers of science in both hemispheres. 



Believe me to be, with much esteem and regard, yours, most truly, 



RICHARD OWEN. 



