566 



HISTOEICAL GEOLOGY. 



strom, the generic name meaning the ancient murderer. Both specimens have 

 traces of spiracles, showing them to have been terrestrial species. 



842. 



Ceratiocaris papilio. Salter. 



The wing of an insect, Palceoblattina Douvillei of Brongniart, has been 

 found in the sandstone of Jurques in northwestern France, and for the pres- 

 ent it is the oldest known insect. Its relation to the Cockroaches, which is 

 thought probable by Brongniart, is questioned by Scudder, a Keuropteroid 

 character being thought more probable. The sandstone is of the age of the 

 May Hill sandstone of England, at the bottom of the Upper Silurian. 

 Jaws of Annelids of several species have been described by Hinde from the 

 Wenlock and Ludlow groups. 



Fish-remains occur especially in the bone-bed below the Tilestones, 

 and also in the Tilestones. Fig. 843 represents a head-shield of Pteraspis 

 Banksii Huxl. & S. Fig. 844 is the head-shield of a Cephalasjns — so named 

 from the Greek for a shield-like head. A complete animal, but different in 

 species, and from the Devonian, is shown in Fig. 980 ; and Fig. 846 repre- 

 sents probably part of the jaw-bone of a Cephalaspis. 



Fishes. — Fig. 843, Pteraspis Banksii, head-shield ; 844, Cephalaspis Murchisonl, inside of head-shield ; 845, spine 

 of Onchus tenuistriatus = Ceratiocaris tenuistriata ; 846, part of jawbone of Cephalaspis(?) ; 847, shagreen 

 pieces (?), Thelodus parvidens. Murchison. 



Fishes of the Shark tribe are supposed to be indicated by spines, teeth, 

 and portions of the shagreen, or skin ; but all are doubtful. A number of 

 Upper Silurian Fishes have been described from the rocks of Russia and 

 Bohemia, including species of Coccosteus and Pterichthys, and the fin-spines 

 of Sharks. 



