8 Ml-. A. S. Woodward on ihc 



Incertic sedis. 



Genus Lophostracon. 



Lo^jJiostracon spitzhergense (Lankester). 



1884. Lophusf racmi spitzheryeiise, E. R. Lankester, op. cit. p. o, pi. ii. 

 fig. 6. 



The ribbed fragment of dermal armour thus named hy 

 Lankester still remains incertce sedis; but two new facts may 

 be added to the original notice. In the first place, when light 

 is allowed to fall upon tlie impression of the superficial orna- 

 ment in a certain direction the ridges are distinctly shown to 

 have been crimped or tuberculated. The published figure is 

 thus not quite accurate. Secondly, the tissue of the plate is 

 coarsely cancellated, and numerous irregularly arranged bone- 

 lacuna3 can be distinguished in microscopical sections. 



It must be remarked, however, that the Spitzbergen 

 Lojihostracon is not unique. So long ago as 1837 Kutorga * 

 described and figured similar fossils from the Lower Devonian 

 of Livonia, erroneously regarding them as referable to a 

 Chelonian under the name of Trionyx sulcatus. Twelve 

 years later, also, Hugh Miller f figured another example 

 from the Old Red Sandstone of Thurso, Caithness, as a 

 " shoulder {i, e. coracoid ?) plate of Asterolepisy All these 

 fossils probably pertain to a large Arthrodiran fish; and they 

 occur upon the same horizon as the genera Ilomostcus and 

 Ileterosteus. 



Form, and Loc. The only known specimen was obtained 

 by Dr. Nathorst from the Eed Sandstone of Dickson Bay. 



Genus Porolepis, nov. 



Syn. Gi/rolepiit, G. Kade (non Agassiz), Programm k. Realschule zu 

 Meseritz, 1858, p. 17. 



An imperfectly recognizable genus, known only by detached 

 rliomboidal scales. Scales moderately imbricating, with a 

 leeble inner ridge, and not united by a peg-and-socket articu- 

 lation ; the exposed surface covered with punctate ganoinc 

 and in tlie antero-supcrior half marked with oblique wrinkles 

 and ridges. 



The distinctness of these scales from those of any known 

 genus was first recognized by Kade, who described examples 



* S. Kutorpa, Ikitr. Geopn. u. Talaout. DorpatV, pt. ii. (IKJD, \\ lo, 

 pi. ii. lips. 1 4. 



t II. Miller, • 1 out print* of the Creator ' (1840). p. 88, fig. 38. 



