82 DR. A. S. AV00DWA.RD ON FISH-REMAINS [March I913, 



smooth granular pieces appear to resemble the tubercles of 

 Thelodus ; but in section under the microscope all the specimens 

 distinctly exhibit bone-cells, and so belong only to higher types of 

 fishes. In all cases the bone-cells occur between parallel laminae, 

 not arranged in haversian systems, the bony tissue being thus 

 of the primitive type described by Pander as is ope din. A few- 

 fragments are larger than the others, and among these, as already 

 recognized by Mr. Proctor, there are characteristic remains of 

 Holoptychius and Bothriolepis. 



One elongate ovoid scale nearly 3 cm. in length (PI. X, fig. 1) 

 shows in impression the typical external ornament of Holoptychius. 

 The longitudinal ridges are large and few, thick and rounded as in 

 H. nobilissimus, not so thin and sharp as in H.jlemingi. They are 

 rarely bifurcated and intercalated, and none are subdivided into 

 tubercles. Their arrangement corresponds closely with that of the 

 ridges on some ventral caudal scales in the type-specimen of 

 H. nobilissimus from Clashbennie (Perthshire). Part of the inner 

 face of the same scale is preserved, exhibiting a peculiar pitted and 

 reticulated structure, which is seen again on the inner face of a 

 second scale of smaller size and more nearly circular shape (PI. X, 

 fig. 2). It may also be added that two or three fragments in 

 microscope-sections of the rock display the curious chevron-pattern 

 formed by the constituent laminae, which has already been observed 

 by M. Lohest 1 in a section of a thick scale of Holoptychius from the 

 Devonian of Belgium. 



Part of the impression of a Holoptychian tooth, about 1 cm. in 

 height, bears marks of its fine longitudinal ridges, with the inter- 

 calated more delicate ridges, extending nearly to the smooth blunt 

 apex. Mr. Proctor made a transverse section of part of this tooth, 

 and observed its dendrodont structure ; but the specimen was 

 unfortunately too fragile for preservation. 



Two portions of dermal plates clearly belong to Bothriolepis, as 

 shown by their pitted external ornament and their cancellous 

 structure (PI. X, fig. 3). Equally thick plates of Holoptychius 

 would be densely laminated, without any conspicuous cavities. In 

 one specimen the superficial pits are smaller and more sharply 

 defined than in the other, but similar variations may be noticed in 

 different parts of the shield of one and the same species of this, 

 genus. 



An internal impression of another piece of dermal armour also 

 seems to be referable to Bothriolepis, and may almost certainly be 

 interpreted as a right posterior ventro-lateral plate. It is bent 

 along its longer axis at an angle somewhat greater than a right 

 angle ; and the margin of the excavated hinder end shows the 

 impression of a wide rounded thickening on the inner face, which 

 would strengthen this part. Traces of the bone itself are seen, and 

 they bear the characteristic pitted ornament. 



1 Ann. Soc. Geol. Belg. vol. xv (1888) Mem. p. 128 & pi. ii, fig. 4. 



