238 J. F. WHITEAVES ON A DECAPOD CÎIUSTACEAN. 



which, occasionally, are surrounded by a minute annulus at the base ; and the three 

 keels each have a single series of larger conical tubercles, whose pointed apices are directed 

 forward. 



In front of the transverse and Y-shaped furrow the carapace is very badly preserved, 

 and the anterior margin with the rostrum is broken off. The two lateral and tubercu- 

 lated keels appear to be prolonged to within a short distance of the front margin of the 

 carapace, though they are somewhat less distinct in front of the transverse furrow than 

 they are behind it. On the anterior side of the furrow the central keel is absent, and the 

 median portion of this part of the carapace bears a number of comparatively large and 

 prominent, distinct and conical tubercles, which are somewhat peculiarly arranged. Next 

 to the fun-ow, and in advance of it, in the median line, there are five tubercles arranged, 

 in two convergent rows of two pairs and an odd one, which, if connected by lines, 

 woiild have much the shape of an isosceles triangle, with its base near to the furrow. 

 Between the space bounded by these five tubercles and each lateral keel, there is a shal- 

 lowly concave and rather broad depression of the carapace. In front of these five tuber- 

 cles, again, there are four others and still larger ones, (the two anterior ones apparently of 

 considerable size), an-anged somewhat in the form of a square, any of whose sides would 

 be greater than the base of the isosceles triangle indicated by the other five. 



The upper surface of each of the abdominal segments bears a tubercle in the centre, 

 on its anterior edge, and another one on the margin of each of the sides. The most prom- 

 inent characteristic of the species, in fact, is the possession of three widely distant, longi- 

 tudinal and tuberculated keels, which extend over nearly the whole length of the upper 

 surface of the body. 



To the right of the carapace, in front, there are indications of what appears to have been 

 a large pinching claw, and, if the appearances presented are correctly interpreted, the 

 sides of the fixed ramus of that claw are also coarsely tuberculated. 



Until its exact generic position shall have been settled by the collection of more per- 

 fect specimens, it may be convenient to designate the present species as Hoploparia (?) 

 Canadensis, though it is by no means certain that it belongs to McCoy's genus of that 

 name. 



