WHITEAVES.J DEVONIAN FOSSILS OP MANITOBA, ETC. 289 



and sinus are rather feebly developed in each, and these specimens from 

 Manitoba correspond much better with examples of A. vlf/a/n from the 

 Hamilton shales of Muscatine and Scott counties, Iowa, kindly forwarded 

 for comparison by Professor Calvin, than with the specimen from the 

 Falls of the Ohio figured by Professor Hall. 



(S.) AtRYPA RETICULARIS, L. 



Plate 37, fig. 8. 



For a full list of synonyms of this species, with references, see Davidson's " Mono- 

 graph of the Britisli Devonian Brachiopoda," page 53, the same author's 

 " British Silnrian Brachiopoda," p. 129, or Hall's " Palaeontology of the State 

 of New York, vol. IV, pt. 1, p. 316. 



" Flat Rock Bay " and north end of Manitoba Island, Lake Manitoba, 

 and Snake Island, Lake Winnipegosis ; Prof. H. Y. Hind, 1858. Point 

 Wilkins, on the west side of Dawson Bay, Lake Winnipegosis, and 

 Warren Island, Swan Lake, Manitoba ; J. W. Spencer, 1874:. Found also, 

 more or less abundantly, in neai-ly all the outcrops of Devonian limestone 

 on the shores, islands and immediate vicinity of Lakes Manitoba and 

 Winnipegosis examined by Messrs. Tyrrell, Dowling and the present 

 writer in 1888 and 1889. Common throughout the whole series, but most 

 abundant above the Stringooephalus zone. 



In the Devonian rocks of the Mackenzie River district, as stated on 

 page 230 of the present volume, the typical A. reticularis and its variety 

 (isjifra are connected by numerous specimens which show intermediate 

 gradations between the finely ribbed and coarsely plicated forms. On 

 Lakes Manitoba and Winnipegosis, the two varieties, which almost 

 always occui' together, are remarkably constant to their respective cha- 

 racters. At each of these lakes the specimens of A. reticularis often have 

 the broad " marginal fringe " or " foliated expansion'' of the ventral valve 

 preserved entire, but, as the matrix in which they occur is a hard dolomite, 

 it is very difficult to reduce such specimens to a portable size without 

 injuring them. The marginal fringe of the specimen figured (from Pen- 

 tamerus Point, Lake Manitoba) is nearly an inch and three-quarters broad, 

 and the shell has a maximum breadth of about four inches and a-half. 



(S.) Atrypa RETICULARIS, var. aspera, Schlotheim. 



For a, list of the synonyms of this shell, with references, see page '22d of the pre- 

 sent volume. 



Localities, collectors and dates practically the same as those for the 

 preceding species. Common also throughout the whole series. 



H 



