WHiTEAVEs.] LARAJIIE AND CRETACEOUS INTERTEBRATA. 87 



CEUSTACEA. 



HopLOPARiA? Canadensis, AVhiteaves. 



Plate. 11. 



Hoploparia .' Canwhnsis, Whiteaves. 1SS4. Proc. and Trans. Royal Soc. Canada, 

 vol. 2, p. 237. 



Highwood Eiver (a tributary of the Bow Eiver), ten miles west of 

 the tii-st fork, E. G. McConnell, 1882 : one specimen. 



The following is a copy of the original description of thi.s interesting- 

 fossil. 



'• The specimen originally consisted of an elongate-oval and flat- 

 tened concretionar}' nodule of soft argillite, with a .small piece broken 

 off' from one end, but enough of the matrix has been removed to show 

 most of the carapace and the upper surface of a few of the abdominal 

 segments. The anterior extremity of the carapace, with the rostrum, 

 is unfortunately not preserved, and the tail, with some of the posterior 

 abdominal segments, was broken off when the nodule was found. The 

 ambulatory feet are preserved, but it was found to be scarcely possible 

 to remijve the soft --hale from around them without running the risk of 

 ^})oiling the specimen. 



The carapace, like that of most of the macrura, is elongated and 

 comparatively narrow, with nearly parallel sides, and, when perfect, 

 its length must have been about twice as great as its breadth. A 

 little in advance of the midlength a single, broadly V-shaped, deep and 

 rather wide groove or furrow cro.^ses the carapace transversely. The 

 posterior half of the carapace is depressed and rather distinctly three- 

 keeled in a longitudinal direction, though it is most likely that these 

 appearances are mostly or wholly due to a considerable and abnormal 

 compression from abjove. Be this as it may, in the sj)ecimen collected 

 by 3Ir. McConnell, a central keel, or narrow but prominent raised ridge, 

 which is about three times as broad posteriorly as it is anteriorly, and 

 which is bounded on each side by a deep and angular farrow, extends 

 from the posterior end of the carapace to the centre of the Y-shaped 

 groove which transvei'ses it. This central keel is much more strongly 

 mai'ked than the broad and comparativel}' obtuse and lateral keels, 

 which latter are placed near the outer margin of each side. The sui-- 

 face of the posterior half of the carapace (and perhaps that of the 

 anterior also) is covered with rather distant, small, isolated conical 

 tubercles, which, under the lens, look as if they might have each borne 



