170 



Found incrusting brachio- 



pods, in the shale four feet 

 below the lowest Trilo- 

 bate bed, in Avery's Ravine 

 (rare). 



Hederella filiformis. 

 (Billings.) (Fig-. 77 A.) (Au- 

 lopora filiformis. Billings, 

 Can. Journ., Vol. IV., p. 119. 

 Pal. N. Y., Vol. VI.. p. 278, 

 PL LXV.) 



Distinguishing Characters. 

 — Parasitic p r o c u m bent 

 habit ; attached for its entire 

 length ; elongate sub-cylin- 

 drical primary axis, with lat- 

 eral simple tubular cells, and occasionally 

 tubular branches; sinuous or tortuous 

 character of cells, with apertures abruptly 

 turned outwards; cell tubes of greater 

 diameter and less length than H. cana- 

 densis. 



Found 

 the Hamilton 

 Creek. (Coll. Am. Mas. Nat. Hist, New 

 York.) 



Fig. 77. Hederella canadensis. A frond 

 natural size, and a portion enlarged, x 12 

 (after Hall and Simpson). 



incrusting 



shells and corals in 

 group of Eighteen Mile 



Fig 77A. Hederella 

 filiformis. Natural size 

 and enlarged, x 6 ( after 

 Hall and Simpson). 



Class Brachiopoda. Cuvier. 



The Brachiopoda are marine animals, sparingly represented in the 

 modern seas, but most prolifically developed in the Palaeozoic and early 

 Mesozoic waters. The soft parts are enclosed in a bivalve shell, for 

 which reason they are often, though erroneously, classed with the Mol- 

 lusca, their true affinities being decidedly with the worms and Polyzoa. 



The valves of the brachiopod shell are dorsal and ventral, and not right 

 and left as in the lamellibranch Mollusca ; they are unequal, and each 

 one is symmetrical with reference to a median line ( longitudinal axis) 

 drawn through its apex. The larger valve (in most species) has its beak 

 variously truncated, or furnished with an opening or foramen, for the 



