94 CANADIAN FOSSILS. 



d. Var. Pauqdettiana. 



Plate XI. Fig. 12. 



A small specimen of brownish, fine-grained limestone (weathering 

 grey, and containing shells), from Pauquette's Rapids, Allumette 

 Island, Ottawa River, contains one well-preserved brown coloured 

 valve (fig. 12), i inch long, ^^ inch broad, much like the largest spe- 

 cimen from Louck's Mill, but showing no marginal rim, and feeble 

 traces only of the eye-spot and its accompanying depression. In this 

 fragment of limestone (probably Trenton) smaller Entomostracous 

 bivalves abound (see p. 99 and 100). 



Except in the relative size, the form of the eye-spot, and the 

 valve-margin (in which latter points one of these larger specimens 

 varies from the others), the two sets of specimens (the large and the 

 small) do not appear to disagree essentially, as far as my means of 

 examination at present enable me to judge. At the same time, as 

 we know that in some recent bivalved Entomostraca, different species 

 and even subgenera may present a great similarity in their carapaces, 

 it is possible that we have here a distinct specific form. 



Mr. Conrad has briefly described,* under the name of Cytherina 

 fahulkes, a bivalved Entomostracan, from the Trenton limestone of 

 Mineral Point, Wisconsin. This appears to be a Leperditia half an 

 inch in length, and therefore surpassing in size the specimens under 

 notice, to which it may be allied. 



See Annals of Natural History, 3rd series, vol. i. p. 340, for 

 descriptions of this and the following variety. 



e. Var. Josephiana. 



Plate XI. Fig. 16. 



A small specimen of grey Trenton limestone, from the east side of 

 St. Joseph's Island, Lake Huron, containing a Bryozoon, and weath- 

 ering yellowish, bears a right valve of a Leperdkia fi inch long, and 

 if inch broad ; there is also a separate perfect carapace of the same 

 form (11 inch thick) from the same limestone. The valves are of a 

 light-brown color ; the eye-spots are indistinct ; the radiate markings 

 of the muscle-spot are more visible on the left than on the right valve; 

 the overlapping ventral edge is neither straight, nor symmetrically 

 curved ; the general form of the lower half of the carapace is rounded 

 and bulky. 



• Proceedings of the Philadelphia Academy, 1843, vol. i. p. 332. 



