184 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



is shallowly concave in the middle. A sliort distance in advance of 

 the neck furrow, on the outer and lower jjortion of the carapace, on 

 each side, there is a very short and transverse groove or narrow con- 

 striction, which may possibly be confluent with the neck furrow on 

 the strongly decurved lateral margins of this part of the carapace. 

 The exact outline of the anterior margin of the carapace cannot be 

 ascertained, and the tip of the rostrum is broken oft". The basal portion 

 which remains is about seven or eight millimetres long. At the base 

 it measures five mm. in breadth, and at the broken anterior extremity 

 its breadth is two mm. Its outer margins are defined by two linear 

 and acute, tuberculated and raised longitudinal ridges, between which 

 the surface is smooth and concavely excavated. 



The whole of the outer surface of the carapace is ornamented by 

 rather distant, isolated tubercles. In its jwsterior moietj- these 

 tubercles are somewliat irregularly disposed, though there is a low, 

 very narrow, and rather inconspicuous keel on the median line, on 

 either side of which the cardiac region is eomjjaratively smooth. On 

 the anterior portion of the carapace the tubercles are grou2)ed some- 

 what obscurely in two or three longitudinal rows on both sides of the 

 narrow median keel, which is continued with greater or less distinct- 

 ness up to the commencement of the rostrum. 



The anterior pinching claws appear to have been unusually 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. 



Sounding Creek, Township 30, Eange 8, west of the 4th Principal 

 Meridian, 1886. 



At the same locality and date, five detached pinching claws of an 

 apjiarently second species of decapod were collected in as many con- 

 cretionary nodules. These claws resemble those of P. ornatus in the 

 comi^arative shortness and robustness of their terminal segments, but 

 the outer surface of the latter is finely granulated rather than coarsely 

 tuberculated. 



FISHES. 



A well preserved tooth of a Selachian was collected on the Battle 

 Eiver, in Township 46, Eange 3, west of the 4th Principal Meri- 

 dian, in 1885; and a pectoral fin, a^jparently of a large Selachian, 

 at Sounding Creek, Township 30, Eange 8, west of the 4th Principal 

 Meridian, in 1886. 



