554 RAMSAY H. TRAQUAIR ON AMBLYPTERUS, 



stitute a new generic type or may be received into any other genus 

 already known. If we now turn to the genus Elonichihys of Giebel*, 

 we shall find that that author characterized the fishes (E. Germari, 

 crassiclens, and Icevis, from the Coal Measures of Weltin, near 

 Halle) which he referred to it, as standing in the middle between 

 Palceoniscus and Amblypterus, allied to the former by their fulcrated 

 fins, and to the latter by the large size of these organs, as well as by 

 the aspect of their thick striated scales, " which remind us of certain 

 Amblypteri" From Palceoniscus, however, he considered them to 

 differ in the want of the " scaly covering on the fins," and from 

 both in the dentition, which consisted of an external series of 

 minute teeth comparable to the " Biirstenziihne " of Amblypterus, 

 between which larger ones of a slender conical shape were seen, 

 " wie ich dieselben weder bei den Pakeonisken noch Amblypteren 

 finde." But, unfortunatel) 7, for this diagnosis, the fins of 

 Palceoniscus are no more covered with scales than those of any other 

 genus belonging to the family, nor are the fulcra wanting in any of 

 the species which have been classed under Amblypterus t, and, 

 finally, it has been shown that more than one of Agassiz's 

 " Amblypteri " possess large laniary teeth quite similar to those of 

 Elonichthys. But although Giebel's conceptions of its relationship 

 to other Palaeoniscoid forms were thus somewhat imperfect, I have 

 convinced myself, by a careful examination of the type specimens 

 in the museum of the University of Halle, that the genus 

 Elonichthys is quite tenable, and that to it the Amblypterus nemo- 

 pterus of Agassiz and the other forms referred to above as specially 

 allied to that species are properly referable. Though closely 

 resembling Rhabclolepis, it differs in the absence of the subopercular 

 plate ; the operculum is also usually more largely developed ; while 

 from Amblypterus, as restricted by Troschel, the dentition and the 

 greater obliquity of the suspensorium are obvious marks of distinc- 

 tion. From Palceoniscus, to which some of the species were 

 referred to by Agassiz, it is distinguished by the large size of the 

 fins, and by the possession of more differentiated laniary teeth in 

 the jaws. Nearly related to Acrolepis, it differs from that genus in 

 the anterior covered area of the scales being reduced to a very- 

 narrow margin ; but from Pygopterus it is widely separated by the 



* Fauna der Vorwelt, vol. i. pt. 3, pp. 249-251. 



t It is remarkable that Agassiz's error in the ' Tableau Synoptique,' as to 

 the absence of fin-fiilcra in Amblypterus, " except on the upper lobe of the tail," 

 though corrected by himself in his general description of the genus, has never- 

 theless been repeatedly copied into the works of subsequent writers, such as 

 Pictet (Pal. 2nd ed. vol. ii. p. 181), Eichwald (Leth. Eossica). 



Giebel, it is true, in his definition of Amblypterus (op. cit. p. 251), does not 

 mention the absence of fulcra as a character ; but nevertheless on this ground 

 ("durchdie Anwesenheit der Fulcra nur an der Schwanzflosse") he transfers 

 Agassiz's Palceoniscus Duvemoyi to this genus. In this transference I quite 

 agree with him, as will be seen further on, but not on that account, the fulcra 

 being obviously present in well-preserved fins of that species. This has been 

 vigorously pointed out by Troschel, who, referring to a specimen in the Bonn 

 Museum, speaks of the fulcra on its anal fin as being "so schon sichtbar, wie 

 man es nur wiinschen kann " {op. cit. p. 17). 



