ANIMALS. 225 



smooth character of the scales, and their large size, — and the limited heterocercism of 

 the tail. In referring to Agassiz's description of P. glapliyrus, I find these are the 

 principal characters assigned to that species, combined with the dentation of the free 

 edges of the scales. The last feature I failed to detect at first sight, in your specimen ; 

 but I have since, with a strong light, discovered two or three scales near the head, having 

 posterior edges perfect, and showing the dentations. There remains, therefore, no 

 doubt on my mind (although the body of the fish is certainly more slender than the 

 one figured by Agassiz), that it is a small P. glaphyrus. Judging from Agassiz's 

 figure, I think the belly scales in the York Museum specimen (vide PI. XXII, fig. 3) 

 are a little dislocated downwards, giving a deeper appearance to the body. In the 

 Whitley specimen, the dislocation and elongation of the head and shoulders tend to 

 convey the idea of more slender proportions than the Fish really possessed. Taking 

 these points into consideration, I do not think the discrepancies sufficient to warrant 

 the establishment of a new species." 



This, which is another rare species, occurs in the Marl-slate at Midderidge, 

 East Thickley, West Bolden, Houghton-le-Spring, Whitley, Rushyford, Ferry Hill, 

 and Thrislington Gap. It has been found, according to Dr. Geinitz, at Mansfeld 

 in the Kupferschiefer. 



PAL.ffiONiscus LONGissiMus, Agassiz. Plate XXI, fig. 2 c. 



PALiEONiscus LONGISSIMUS, Agussiz. Poiss. Foss. vol. ii, p. 100, pi. x c, fig. 4. 



— — „ Ann. Mag. Nat. Hist., vol. vii, p, 495, 1841. 



— — „ Morris, Catalogue, p. 201, 1843. 



— — „ Rep. 13th Meet. Brit. Assoc, p. 198, 1844, 



— — „ De Verneuil, Bull. Soc. Geol. de France, 2"^ serie, 



vol. i, p. 38, 1844. 



— — „ Geol. Russ., vol. i, p. 227, 1845. 



— — „ Tennant, Strat. List, p. 89, 1847. 



— — „ King, Catalogue, p. 14, 1848. 



— — „ Howse, Trans. T. N. F. C, vol. i, p. 233, 1848, 



This elegant fish, so well characterised by its specific appellation, has been found 

 in Marl-slate at East Thickley, Midderidge, West Bolden, and Houghton-le-Spring. 

 The beautiful specimen figured, and now in the Newcastle Museum, was got out of 

 the same bed at Thrislington Gap. The Whitby Museum contains a specimen, 

 apparently of this species, which was found by Miss Green of South Shields in the 

 Limestone on the coast of Durham, a little north of Marsden. 



Pal^eoniscus macropthalmus, Agassiz. Plate XXII, fig. 2. 



Pal^oniscus macropthalmus, Agassiz. Poiss. Foss., vol. ii, p. 99, pi. x c, fig. 3. 



— — „ Ann. and Mag. Nat. Hist., vol. vii, p. 495, 



1841. 



— — „ Morris, Catalogue, p. 201, 1843. 



dd 



