Section IV., 1884. [ 237 ] Trans. Roy. Soo. Canada. 



XIII. — Note on a Decapod Crustacean, from the Upper Cretaceous of Higliwood River, 

 Alberta, N. W. T. By J. F. Whiteaves. 



(Read May 21, 1884.) 



Remaius of crustaceans allied to the lobster and crab of recent seas, though compara- 

 tively frequent in the Cretaceous rocks of Europe and the United States, have not yet 

 been recorded as occurring in deposits of the same age in Canada. 



In 18*76, however, while engaged in studying the fossils collected by Mr. James Rich- 

 ardson from the Lower Shales of Skidegate Inlet, in the Queen Charlotte Islands, which 

 are now believed to be the equivalents of the G-ault, and in attempting to remove the 

 matrix which covered one side of an Ammonite, the writer had the good fortune to expose 

 to view a nearly perfect specimen of a small crab, which has been sent to Dr. Henry 

 Woodward, of the British Museum, for examination and description. 



The fossil, which it is the more immediate object of this paper to describe, is a rather 

 remarkable example of a macrurous decapod or lobster-like crustacean, collected by Mr. 

 R. Gr. McConnell. in 1882, from the Cretaceous shales of the Highwood River, a tributary 

 of the Bow. 



The specimen originally consisted of an elongate-oval and flattened concretionary 

 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 remove the soft shale from around them without 

 running the risk of spoiling 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 midleugth a single, broadly Y-shaped, deep and 

 rather wide groove or furrow crosses 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 above. Be this as it may, in the specimen collected by Mr. Mc- 

 Connell, 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 furrow, extends from the posterior end of the carapace to the centre of the 

 V-shaped groove which transverses it. This central keel is much more strongly marked 

 than the broad and comparatively obtuse lateral keels, which latter are placed near the 

 oïiter margin of each side. The surface 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 a bristle at the summit, and 



