142 Annals of the Carnegie Museum. 



to include the so-called " Palfconlsci" of the American Trias, or those 

 forms which are now commonly referred to the genus Seviionotus, 

 The identity between Ischypterus Egerton and Semionotns Agassiz 

 was suspected by Newberry, clearly recognized by A. Smith Woodward, 

 and is now generally admitted. 



With the exception of L. Agassiz, Sir Philip Egerton was probably 

 the leading authority of his time on fossil fishes. His notes on the two 

 principal genera of American Triassic fishes, incorporated in Lyell's 

 paper of 1847, are exceedingly brief, and it is to be regretted that he 

 did not continue his study of these forms. Some further light in 

 regard to his views has, however, been preserved in unpublished 

 correspondence between the two eminent scientists, Egerton and 

 Lyell. Copies of two letters written by the former to the latter in 

 1844 appear to have been sent to Professor Silliman of Yale, who 

 collected part of the material reported upon, and through him to have 

 reached the Redfields, by whom the documents were preserv'ed. At 

 all events the manuscript containing Egcrton's views has been stored 

 away for many years in the cabinet containing the Redfield Collection 

 of fossil fishes at the Peabody Museum of Yale University. For the 

 l)rivilege of now bringing to light these early memoranda, and of 

 studying a number of well-preserved specimens in the collection at 

 Yale, the writer is indebted to the kindness of his friend Professor 

 Charles Schuchert, Director of the Peabody Museum. The text of 

 the correspondence is as follows: 



"Oulton Park, Tarporly, Dec. 18, 1844. 

 "Dear Lyell: 



"There are two species of Chclonichtliys, Asmiissi and mi}wr, both 

 found in the Old Red of Riga (Russia) and of Elgin. I have the latter 

 also from Orkney. It is the largest of the Old Red fishes I am ac- 

 (piainted with. The days are so dark that I cannot do much at your 

 Black Fish. I have, however, taken out and examined the Catopteri. 

 This is a very good and well marked genus of Redfield, and deserves 

 a more ample description than he gives it. I find two species, the one 

 C. gracilis, the other new, which you may call if'you please C. Redfieldi. 

 It is nearly as large as C. gracilis, but much deeper. The bones of 

 the head are ornamented with closely packed flattened tubercles, which 

 also extend over the nuchal scales and the scales immediately posterior 

 to the thoracic cincture. 



