400 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



species. Excepting the rare form found at Chicopee, it will be seen that 

 they are all referred to two ganoid genera, Ischyptenis of Sir Phillip 

 Egerton, which is characterized by the great strength of the fin rays, and 

 Catopterus, distinguished by the posterior position of the dorsal fin. 



Most of the specimens found belong to the two species Ischypterus 

 tenuiceps and Catopterus gracilis. 



Ischypterus ovatus. W. C. Redfield. Suuderland (Redfield), Turuers Falls (New- 

 berry). 



Ischypterus marshii W. C. R. Suuderland (Redfield). 



Ischypterus micropterus N. Suuderland. 



Ischypterus tenuiceps Ag., sp. Turners Falls. Suuderland. Figured by E. Hitch- 

 cock. Geol. Mass., 1841, Vol. II, p. 459, PI. XXIX, flgs. 1, 2. 



Ischypterus mctcropterus W. C. R. Sunderland. 



Ischypterus parvus W. C. R. Suuderland. Figured by Hitchcock, Geol. Mass., 

 1835, Atlas XIV, fig. 44, and 1841, PI. XXIX, tig. 3. 



Ischypterus latus J. H. R. Sunderland. 



Ischypterus elegans. Sunderland. 



Catopterus gracilis J. H. R. Sunderland. 



Catopterus par vulus W. C. R. Suuderland. 



Acentrophorus cMcopensis N. Chicopee Falls. 



ICHNOLOGY. 



Since the publication of the Ichnology of Massachusetts and its Sup- 

 plement, which President Hitchcock looked upon as closing the most 

 original scientific investigation of his life, but little has been done to 

 advance the knowledge of this the most peculiar contribution of the Con- 

 necticut Valley to geology, except what has been published by Prof 

 C. H. Hitchcock, who has kindly permitted me to print in this place a 

 jjortion of an article upon the subject, containing his latest views upon the 

 classification of these forms, from the proceedings of the Boston Society 

 of Natural History, Vol. XXIV, 1889, p. 117. The article has been cor- 

 rected by Professor Hitchcock (1892). 



Recent Progress in Ichnology. 



By C. H. Hitchcock. 



The study of the Ichuozoa, or the animals that made the tracks, naturally 

 divides itself into three parts: First, an examination of the ichnites themselves; sec- 

 ond, the restorations of the animals from their bones, and third, comparisons of the 



