No. l8.] TRIASSIC FISHES OF CONNECTICUT. fl 



Extra-limital Species of Semionotus. 



At least three other valid species of Semionotus, besides those 

 already enumerated, have been described from the Trias of 

 Eastern North America. These are, 5\ lineatus, elegans, and 

 brauni of Newberry. They are all confined to the New Jersey 

 area, so far as known, and the last-named is from the very base 

 of the Trias in that state, being separated from the Boonton 

 horizon by an interval of several thousand feet. The limits set 

 to the present Report do not admit of elucidating the characters 

 of these species, which can by no possibility be confused with 

 the members of our local fauna. Nevertheless, it has been 

 thought desirable to offer an illustration of the form which 

 has been appropriately named S. elegans by Newberry (Plate 

 V), and also to show the head-portion of the type specimen of 

 5. nilssoni (Plate VI), which enabled Agassiz to decipher the 

 main elements of the cranial structure of this genus. 



To the list of imperfectly defined or doubtful species, the 

 status of which is merely provisional, must be added the names 

 of the so-called Ischypterus parvus, founded upon a figure pub- 

 lished in Hitchcock's Geology of Massachusetts, in 1835 ; 

 Ischypterus minutus Newberry, from Durham, Connecticut; and 

 Ischypterus beardmorei Smith, from Boonton, New Jersey. Of 

 uncertain position also are the obscure remains of a Semionotus- 

 like form described by Newberry under the name of Acentro- 

 p horns chicopensis, the few known examples of which have been 

 obtained from metamorphosed sandy shales near Chicopee Falls, 

 Massachusetts. 



It will be convenient to notice at this point the status 

 of an imperfectly known European form, described in the first 

 instance by Deecke as a species of Semionotus, and recently made 

 the type of a distinct genus (Perleidus) by De-Alessandri, who 

 places it in association with the Catopteridse. The type species, 

 P. altolepis (Deecke), occurs in the Ladinian beds of Perledo, 

 Lombardy, and the original specimen upon which it is founded 

 is preserved in the Senckenbergian Museum at Frankfurt. 

 Deecke, in describing the species, remarked that it appeared to 

 him to denote a transitional stage between the genera Semionotus 

 and Pholidophorus. Schellwien. who later examined the speci- 

 men, doubted whether it could properly be included in the genus 



