1870.] ^"'^ [Cope. 



six inches from same point, 7.5 inches. The second uncertain fragment 

 is long and with parallel margins. The outer face is strongly convex ; 

 the imier, at one extremity concave, so that a section would be half a cres- 

 cent (the lower portion being lost). The inner face graduahy becomes 

 convex, though not strongly so, and the long diameter is transverse, while 

 it is vertical at the anterior end. The former is seven inches ; the latter 

 eight inches. The fragment looks like the extremity of a pre maxillary 

 bone, possibly a maxillary, but it is scarcely appropriate to the premaxil- 

 lary already described. 



The periotic hones of the left side were x^reserved almost entire. The 

 buUa has the flat inferior face of the genus Balasna, and the periotic pro- 

 cesses are exceedingly short, shorter even than those of the species of Bal- 

 sena (B. mysticetus and B. cisarctica). The external process is not longer 

 than the posterior, and is compressed and deeply grooved longitudinally 

 below. The posterior process is at right angles to the exterior, and as 

 broad as long. It bears a sublongitudinal ridge near the middle of its in- 

 ferior face ; anterior to it, separated by an interval a transverse ridge oc- 

 curs to which the edge of the thin lip of the bulla is attached. The an- 

 terior process contains the usual foramina, and is broader than long. The 

 superior face of these bones is quite rugose. The buUa is more flattened, 

 i. e., has a shorter vertical diameter, than either that of Balsena mystice- 

 tus or B. cisarctica. The circumference is not a sharp edge as in B. cis- 

 arctica, but is truncate and rugose, at the inner extremity most So. At 

 the external extremity the face gives way to a rounded edge. The infe- 

 rior face is coarsely impressed punctate, and has a curved depression inside 

 the anterior margin. The posterior margin is marked by the usual three 

 grooves with intervening enlargements. The general outline, viewed from 

 below is hexagonal, with the lengths of the sides as follows, beginning 

 with the longest; posterior, anterior, interior, postero and antero-exlerior 

 equal, antero-interior very short. The bulla of B. cisarctica exhibit a 

 long posterior and long interior side, connected by an arched outline. 



The vertebrcB are those of the genus Balsena. The general form of the 

 centra of anterior lumbars and caudals, is abbreviated, especially the lat- 

 ter. The diapophyses of the formsr are thick at the base ; one of those 

 preserved may be a posterior dorsal, but the ends of the diapophyses are 

 not preserved. In a caudal with very short diapophyses, which are a little 

 nearer the basis of the chevrons than that of the neural arch, a small for- 

 amen penetrates the centrum from a point three inches above the base of 

 the diapophysis, and issues at a point 2.5 inches below it. The articular 

 faces are convex ; there is a small rugose central area, and an external an- 

 nular space with coarse concentric ridges. 



Measurements. 



Ft. In. Lin. 



Length of fragment of 0. maxillare to ex- 

 tremity which reposes on frontal 9 8 



Width of same (with left premaxillary) at 43 

 inches from extremity 16 



