EXTINCT ANIMALS 



the oldest remains of fishes which have been 

 discovered. These last two — ^Birkenia and 

 Lasanius (Figs. 190, 191) — are very puzzling 



Fig. 190. — Outline drawing of the Silurian fish Birkenia 

 from Scotland, described by Dr. Traquair. 



little creatures, with spines set in a row along the 

 belly. It is difficult to make out back from 

 belly or to distinguish eyes or mouth, yet they 

 show characteristic fish tails and a scaly cover- 



FiG. 191. — Outline drawing of Lasanius, another genus of fish 

 similar to that drawn in Fig. 190, and from the same 

 locality, described by Dr. Traquair. 



ing of the body. These are among the most 

 recent discoveries and come from the Upper 

 Silurian strata of Scotland. Specimens of these 

 are in the Natural History Museum, but the 

 finest series are in the Edinburgh Museum, 

 where Professor Traquair has made a special 

 study of the most ancient fish remains, the 



262 



