400 Dr. S. JTuodward — Cretaceous Canadian Crustacea. 



either side of whicli the cardiac region is comparatively smooth. Oa 

 the anterior portion of the carapace the tubercles are grouped 

 somewhat obscurely in two or three longitudinal rows oa both 

 sides of the narrow median keel, which is continued with greater 

 or less distinctness up to the commencement of the rostrum. 



" The anterior chelse appear to have been short and robust, while 

 their surface is distinctly tuberculated. The portions of the posterior 

 ambulatory legs that happen to be preserved, on the other hand, 

 are very slender, and their surface is minutely granulated. The 

 abdominal segments are badly preserved, but their outer surface 

 seems to have been smooth, though a narrow median keel can be 

 traced throughout the greater part of their dorsal surface. 



" Locality : Sounding Creek, Township 30, Eange 8 ; west of the 

 4th Principal Meridian, 1886. 



'' At the same locality and date, five detached chelae, apparently of 

 a second species of decapod Crustacean, were collected in as many 

 concretionary nodules. These claws resemble those of P. ornatus 

 in the comparative shortness and robustness of their terminal 

 segments, but the outer surface of the latter is finely granulated 

 rather than coarsely tuberculated." 



Eetma Dawsoni, H, Woodw., sp. no v. (PI. XVI, Fig. 2.) 



Among the specimens which form a second collection sent by 

 Dr. J. F. Whiteaves (24th September, 1898) from the Geological 

 Survey of Canada, is the half of a nodule containing an Astacidean 

 from the Upper Cretaceous of the north-east side of Hornby Island, 

 British Columbia, collected by Mr. J. B. Bennett in 1898 (No. 55d). 



The Crustacean is seen in profile on the split surface of a nodule, 

 and exhibits the cephalothorax, with its stout pair of chelate limbs 

 (or forceps) attached, and the remains of the four pairs of succeeding 

 ambulatory legs, the six abdominal somites, and the telson, but 

 the lateral lobe of the tail-fin was probably preserved in the other 

 half of the nodule not sent. The branchiostegite (covering the 

 branchiae) is broad and tumid, and the branchiocardiac groove is 

 strongly marked. Starting from the median dorsal line as a V-shaped 

 furrow, about 12 millimetres from the posterior border, it bends 

 rapidly forward, becoming deeper on each side, and reaches the 

 lateral border 24 mm. in advance ; here it unites, close to the 

 hepatic lobe, with the equally deep but more transverse cervical 

 furrow, which crosses the carapace 10 mm. nearer to the front. 

 In advance of the cervical groove the postorbital ridge and spine 

 can be seen, also the base of one of the antennules, with part 

 of one of its flagella, beneath the somewhat short rostrum, and 

 lower down the base of one of the outer and larger antennee. 

 The surface of the branchiostegite is marked by numerous small 

 tubercles scattered irregularly over the surface. The branchial, 

 cardiac, and hepatic regions- are also similarly tuberculated, and 

 very tumid. Length of carapace 48 mm., depth of side 25 mm. 

 The ambulatory limbs are fairly long and slender ; the chelate 

 limbs measure about 60 mm. in length ; length of penultimate 



I 



