BIHANMi TILL K. SV. VET.-AKAD. IlANDL. BAND 'iO. AFD. IV. A':0 10. 5 



from the iniddle of the exposetl ridged ornameut. These 

 niarkings are suggestive of the radiating lines of minute 

 tubercles which often extend npon the anterior overlapped 

 margin of the scales in Holoptychius. 



On the same slab as the last specimen (no. 7) there is a 

 small dee])ly-ovate scale, 0-02 m. in vertical diameter, which 

 actually shows the radiating lines of minute tuhercles just 

 mentioned. Another imperfect scale, preserved in impression 

 (no. 8), displaj^s them even more satisfactorily (fig. 6). 

 Here the delicate radiating lines are observed to extend över 

 the greater part of the anterior covered area of the scale 

 (a)- while the delicate ridges of the exposed portion (h) ex- 

 hibit scarcely any convergence posteriorly. 



Another small round scale (no. 9) is interesting for the 

 extent to which the ridged ornament is subdivided into 

 tubercles (fig. 7). Only part of the outer face (b) is ex- 

 posed in impression by the removal of the bony tissue of 

 the scale, but the tuberculations near its hinder börder are 

 ver}' conspicuous. 



The ornament on some of the small scales, however, is 

 by no means iine or subdivided into tubercles. One elongate- 

 oval specimen (no. 10) has very coarse ridges, which con- 

 verge behind and sometimes bifarcate in front (fig. <S); 

 while another imperfect scale (no. 11), of rather different 

 shape, is equally coarsely marked (fig. 9). 



From these descriptions it is evident that the ornamen- 

 tation of the Holoptychian scales from East Greenland is 

 very variable. The ridges on some are much coarser tlian 

 on others, while the extent to which they pass into tubercles 

 at the hinder börder varies considerably. Moreover, a few 

 scales exhibit radiating rows of minute tul)ercles on the an- 

 terior overlapped portion, while the majority are quite smooth 

 on this area. These differences, however, are no greater 

 than those which can be observed on various parts of the 

 body in the type specimen of Holoptychius nohilisfihnus, 

 Agassiz, in the British Museum. In fact, on comparing the 

 Greenland fossils directly with the latter, it seems impossible 

 to discover any distinctive characters sufficient to justify the 

 reference of the scales now described to any other spe- 

 cies. The largest fragmentary scales (nos. 1, 2) are precisely 

 like those of the anterior part of the flank of H. nohiliashiiui). 



