562 RAMSAY H. TRAQTJAIR ON AMBLYPTERUS, 



already referred to, its resemblances are especially striking, viz. to 

 Semionotus Bergeri, Ag. *, of the German Keuper, and Lepidotus 

 minor of the English Purbeck. 



Fishes of this genus occur in the Triassic strata of North 

 America ; it is also said to have been found in the Lower Permian 

 schists of Autun, in Prance t. 



VI. Type of Palcuoniscus glaphyrus, Ag. ( ? Genus Acentrophorus, 

 Traquair). I have not seen the type specimen of this rare species 

 from the English Marl Slate ; but, to judge from the figures given in 

 the ' Poissons Fossiles ' J and in King's ' Permian Fossils ' §, the 

 conclusion seems unavoidable that it is neither a Palosoniscus nor a 

 member of the family of Palaeoniscidie. Certain suspicious details 

 occur in Agassiz's description — for instance, that the mouth is 

 " tres -petite," also that the fulcra "different de ceux des antres 

 especes en ce qu'il sont plus allonges et moins serres contre le bord 

 des nageoires." This latter condition is very distinctly represented 

 in the figure of the species, in which we also miss the prominent 

 heterocercy characteristic of the Palaeoniscidae : in fact the entire 

 aspect of the fish, as there delineated, is eminently suggestive of its 

 affinity to the three little species from Fulwell Hill, Durham, 

 described by Mr. Kirkby as Palceoniscus varians, Abbsii, and alius |j, 

 but whose reference to that genus is certainly erroneous. Until, 

 however, the type specimen is reexamined, it would be unsafe to 

 pronounce as to the generic identity of P. glwphyrus with these 

 last-mentioned forms : at least one marked distinction is found in 

 the denticulation of the scales in the former, a difference which may 

 possibly be only of specific importance. 



But as regards the noii-palaeoniscoid nature of the Fulwell-Hill 

 fishes there cannot be the smallest doubt : and although these species 

 are not Agassizian, it may not be altogether out of place here to 

 devote a little more attention to them than a mere passing reference. 

 That they are not Pal wnisci has been already pointed out by Dr. 

 Liitken, of Copenhagen, in the following terms, " But already in 

 the D}-as we find, alongside of a preponderating number of 

 hetero cereal forms, a few half-homocercal ones." And in a foot- 

 note appended to the same passage he says, " as, for example, 

 Palceoniscus Abbsii, varians, and altus from the English Permian 

 formation, which should be expelled from the genus Palceoiiiscus 

 (like the North- American Triassic species, also previously referred 

 to Palceoniscus, which are now called Iscltypterns, Gatopterus, 



* Poissons Fossiles, vol. ii. pt. 1, p. 224-227. Striiver in Zeitschr. der 

 deutschen geol. Gesellsch. xvi. 1864, pp. 303-330, pi. xiii. 



t The statement that "at Autun, in France, we find the genus Ischypterus 

 accompanying the true Palcsonisci" is made by Sir Charles Lyell (Quart. Journ. 

 Geol. Soc. iii. 1847, p. 278) ; but Sir Philip Grey-Egerton, three years later, states 

 that he is not cognizant of any species of the genus being found there (ibid. vi. 

 1850, p. 8). 



\ Atlas, vol. ii. tab. 10 c. figs. 1 and 2. 



§ PI. xxii. fig. 3. 



|| Ann. & Mag. Nat. Hist. (3) ix. 1 8(>2, pp. 267-269, also in Quart. Journ. Geol. 

 Soc. xxi. 1865. pp. 345-358. 



