WHITEAVES.] CRETACEOUS FOSSILS, NORTH WEST TERRITORY. 173 



two nearly equal jjarts, each of which is subdivided into three spread- 

 ing branchlets with bifurcate or trifurcate apices. Between the first 

 and second lateral saddles there are two rather small auxiliary saddles, 

 the outermost of which is the larger and the more subdivided of the 

 two. The second lateral saddle is deeply divided near the centre into 

 two unequal parts, the outer one of which bears four short incised 

 branchlets and the inner five. The third lateral saddle is so deeply 

 divided in the middle as to form two almost independent saddles. Of 

 these, the outer one, which is the larger of the two, bears three 

 branchlets at its summit, and the inner one two. The fourth lateral 

 saddle is somewhat similar to the third, but a little smaller. The fifth, 

 sixth and seventh, which are still smaller and decrease gradually in 

 size toward the suture, are rather omarginate than branched at their 

 summits. 



The siphonal lobe is about equal in height to the first lateral lobe. 

 On each side the former bears two spreading latei'al branches, which 

 trifurcate at their summits, besides a short, erect, incised sj>ur next to 

 the siphuncle above, and a similar but spreading spur or ofliset at the 

 base. Between the siphonal and first lateral lobes, as also between the 

 first and second, second and third, and thii-d and fourth lateral lobes, 

 there are three small auxiliary lobes, of which the central one is always 

 the largest. The first lateral lobe is broad in its basal and undivided 

 portion, which bears a lateral incised sjjur or oftset on each side. Its 

 upper moiety is deeply divided into two branches of unequal size, viz., 

 into an outer and smaller one which bifurcates above and an inner or 

 larger one which trifureates above, while both widen outward and ulti- 

 mately throw of a number of minute and more or less deeply incised 

 lateral branchlets or spurs. The second lateral lobe is shorter and much 

 narrower than the first. Though its apex is minutely bifid, the lobe it- 

 self is not deeply divided above, but it bears on each side three irregu- 

 larly incised spurs or offsets, which also widen a little outward. The 

 third lateral lobe is much shorter than the second, and its upper portion 

 is divided into two branches which trifurcate on their outer sides. The 

 fourth is smaller, but in other resjiects similar to the third, and the 

 rest of the lobes, which are not branched but incised at their margins, 

 are very small, and decrease graduallj^ and regularly in size to the 

 suture. 



Dimensions of the only specimen collected : greatest diameter, ninety 

 six millimetres; maximum breadth, twenty-six mm.; greatest width 

 of the umbilicus, nineteen mm. 



One remarkably well preserved and nearly pei-fect cast of the 

 interior of the septate portion of the shell; which shews the finest de- 

 tails of the lobes and saddles over nearly the whole of its surface, ex- 



