552 RAMSAY H. TRAQUAIH ON AJIBLYPTERTS, 



AMBLYPTERUS. 



The species referred to Amblypterus in the " Poissons Fossiles " 

 certainly fall into at least five distinct types : — 



I. Type of A. latus, Ag. (Gemis Amblypterus, A.g., restricted). The 

 body is rather deep ; the scales smooth ; the fins large and many- 

 rayed, with minute fulcra ; the dorsal placed a little further back 

 than in the next type ; the caudal powerful. The suspensorium is 

 not so oblique as in the PalaBoniscidae in general ; hence the position 

 of the operculum is more vertical, and the gape proportionally less 

 extensive. There is no small plate (suboperculum) intercalated 

 between the operculum and the interoperculum. The teeth are 

 minute and very slender ; there are no large conical laniaries ; 

 hence the term "en brosse" is here more applicable than in any 

 other genus of Paheoniscidos. 



To this type the title Amblypterus should be strictly limited as 

 recommended by Troschel ; but I must also add that I am unable to 

 see any tangible grounds of distinction between these forms and the 

 smooth-scaled Palceoaisci of the type of P. Duvernoyi, whose recep- 

 tion into the genus Amblypterus is therefore to be recommended. 

 To this point I shall, however, return further on under PaZceoniscus. 

 A. latus and lateralis are characteristic fossils of the Lower Permian 

 strata of Saarbriicken and Lebach ; and the other species, which I 

 propose to unite with them generically, also occur in strata of 

 similar age in Germany, Bohemia, and France ; so that Amblypterus 

 must be deleted from the list of Carboniferous genera, in spite of the 

 length of time during which geologists have been accustomed to 

 look upon it as one of the characteristic forms of the Coal-period. 



IT. Type of A. macropterus, Ag. (Genus Rhabdolepis, Troschel). 

 The scales are moderate, finely striated ; the fins large, many-rayed, 

 with minute fulcra ; the dorsal placed nearly opposite the interval 

 between the ventrals and the anal, the base of the ventrals not 

 specially extended ; the caudal powerful. In each jaw there is a 

 row of stout conical laniary teeth, external to which is a series of 

 smaller ones. The dentition, thus quite conformable to that in 

 Acrolepis or Pygopterus, would alone be sufficient to demand the 

 separation of these forms from the true Amhlypteri ; but careful 

 examination reveals still further differences in the structure of the 

 head. The suspensorium is very oblique, the operculum small ; and 

 between it and the square-shaped plate hitherto considered as 

 " suboperculum," but which I have now come to look upon as 

 interoperculum, there is another of a narrower form (suboper- 

 culum). 



For fishes of this type, which have as yet only occurred in strata 

 of Lower-Permian age, the genus Rhabdolepis of Troschel must be 

 maintained. The presence of the subopercular plate distinguishes 

 this genus from Elonicliihys of Giebel, the form and extent of that 

 plate as well as the shorter base of the ventral fins from 

 Cosmoptychius (mini). 



III. Type of A. striatus, Ag. (Genus Cosmoptychius, Traquair). 



