179 



Found incrusting' braehio- 

 pods, ill tlie shale four feet 

 below the lowest Trilo- 

 bite bed, in Avery's Ravine 

 (rare). 



Hederella fi LI for mis. 

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

 loponi filiformit-f. Billings, 

 Can. Jonrii., Vol. IV., p. 119. 

 Pal. N. Y., Vol. VI.. 1). 278, 

 PI. LXV.) 



Distinguishing Characters. 

 — Parasitic procniiibent 

 habit; attached for its entire 

 length ; elongate snb-cjlin- 

 drical primary axis, with lat- 

 eral simple tubular cells, and occasionally 

 tubular branches ; sinuous or tortuous ^ 

 character of cells, with apei-tures abruptly ^ 

 turned outwards; cell tul)es of greater 

 diameter and less length than H. cana- 

 densis. 



Found incrusting shells and corals in 

 the Hamilton group of Eighteen Mile 

 Creek. (Coll. Am. Mus. Nat. Hist. New 

 York.) 



Fig. 77. HedcrcHa canaden.<iis. A frond 

 natural .size, ami a portion enlarged, x 12 

 (after Hall and Simpson). 



Fig 77 a. Hederella 

 pli/ornii.s. Natural size 

 and eiilai-^ed, x 6 ( after 

 Hall and Simpson). 



Class Brachiopoda. Cuvier. 



The Brachiopoda are marine animals, sparingly represented in the 

 modern seas, but most prolitically 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 furuisiied with an opening or foramen, for the 



