BRACHIOPODA. 
285 
Shell-substance impunctate externally, but the inner laminae are sparsely 
perforated. 
Type, Stringocephalus Burtini, Defrance. Middle Devonian. 
Observations. This old and well known genus has been discussed by many 
wi iters, but to King, Suess and Qdenstedt our knowledge of its internal 
structure is especially due. Its characters are extravagant and its com¬ 
position is peculiar and unique, the genus standing quite apart from other tere- 
bratuloids. Whence its origin is still a mystery. The duration of the type 
was brief, though its development was abundant and characterized a distinct 
horizon of the middle Devonian, the “ Stringocephalus beds.” Its presence, 
however, has not been widely known outside of Germany and England, and 
hence its recent discovery by Whiteaves in the Mackenzie River Basin of 
British North America, is of much interest. Here it is associated with various 
middle Devonian species. 
Authors are pretty generally agreed that the different specific designations 
which have been suggested for slight variations in form, etc., are based upon 
minor characters, insufficient to separate them from the type-species, S. Burtini, 
The S. Bohemicus, Barrande,* is a much earlier form (P. 2 ,) whose generic char¬ 
acters are entirely uncertain. 
* Systeme Silurien, vol. v, p. 218, pi. 83, iv. 
