Parr II. Sxcv. iii. (7.) § 1.] DEVONIAN. 697 
brachiopods is Stringocephalus—a genus allied to Terebratula, but 
entirely confined to this geological system (Fig. 330). Another 
characteristic terebratula-like form is Rensseleria. | 
The known Devonian lamellibranchs number 90 genera and 900 
species, belonging chiefly to the genera Pterinea, Cardiola, Megalodon, 
I 2 — xo" 

Fic. 329.—DEVONIAN AND OLD RED SANDSTONE CRUSTACEA. 
a, Estheria membranacea (Jones), nat. size and magnified (Lower Old Red Sandstone) ; 
b, Entomis (Cypridina) serrato-striata (Sandb.), nat. size and magnified (Upper 
Devonian) ; c, Eurypterus pygmeeus (Salt.) (Lower Old Red Sandstone); d, Ptery- 
gotus anglicus (Ag.) (Lower Old Red Sandstone); e, Phacops latifrons (Bronn) 
(Lower Devonian); /, Bronteus flabellifer (Goldf.) (Lower Devonian); g, Homa- 
lonotus armatus (Burm.) (Lower Devonian). 
Grammysia, Cucullea, Curtonotus, Lucina, and Aviculopecten ; Pte- 
rinea being specially abundant in the lower, Cucullea and Curtonotus 
in the upper subdivision of the system. The most important genera 
of gasteropods are Huomphalus, Murchisonia, Loxonema, Macrocheilus, 
and Plewrotomaria, with the heteropods Bellerophon and Poreellia. 
