SCHULTE, SEI WHALE. 483 



bral surface of the nasal capsule. The mesethmoid in which no centre of ossification has yet 

 appeared, is represented by a very thick plate of cartilage continuous caudad with the pre- 

 and basisphenoid and extending the whole length of the rostrum without as yet a sign of division 

 into parts. To its ventral margin is applied the broad trough-like vomer. The cerebral surface 

 of this extensive cartilage rises in the midline in a low sagittal ridge to which is attached the falx 

 cerebri. The lateral area of the nasal capsule has ossified on its cerebral surface, which has a 

 quadrangular outline and abuts by its caudal end upon the orbito-nasal fissure. This lateral 

 ethmoid is joined to the mesethmoid by a delicate cribriform plate, which is slightly depressed 

 and contains three rather large foramina. It is still cartilaginous. 



The axial elements of the cranium are all remarkable for their transverse breadth, especially 

 is this true of the sphenoidal segments, and further for the low relief of their projections, notably 

 the dorsum sellse. There are no clinoid processes. As a whole the brain-case is less elongated 

 than in deBurlet's foetus, but is still far from the shortened condition of the adult, from which 

 it further differs in the lack of any pronounced bending at its junction with the rostrum. 



Mandibula. The mandible is strongly arched, measuring 87 mm. along its convex ectal 

 surface and but 75 mm., along the arc of this curve. Its height at the coronoid process is 

 13.5 mm., at the condyle 12 mm. It differs from the adult bone in the massive proportions of 

 its proximal portion, which far exceeds the body in its vertical and transverse dimensions. The 

 condylar process is better developed, and is distinctly produced craniad, so that the margin of 

 the mandibular notch ascends distinctly towards the articular surface. The ventral margin 

 rostrad of the angle is slightly convex becoming straight below the coronoid. In consequence 

 the whole post-coronoid portion of the jaw has a slight ascent, the reverse of its direction in 

 the adult. The articular surface is ovoid, with its major axis obliquely directed craniad, mesad 

 and rostrad, and in this direction narrowing to a blunt point. It is covered by a thick fibrous 

 pad which joins it to the glenoid fossa. I could make out no synovial cavities, but the tissue 

 adjacent to the bones was loose and easily stripped off. A firm capsule was attached at the 

 circumference of the condyle. An oblique, shallow groove separates the condyle from the re- 

 gion of the angle, which is elevated and massive giving attachment to the depressor mandibulae. 

 The coronoid process is high and triangular, its caudal margin vertical and slightly concave. 

 Entally a deep groove separates the condyle from the angular process which is strongly marked 

 and massive. In the groove is attached the internal pterygoid muscle. The mandibular 

 foramen is large, the' lingula but little developed and more nearly horizontal than in the adult. 

 Meckel's cartilage is lodged in a groove near the ventral margin, and is visible on the surface 

 from the mandibular foramen almost to the symphysis though much diminished in size distad. 

 From the interval between the mandibular foramen and the insertion of the depressor craniad 

 the cartilage is free, passing mesad of the temporo-maxillary articulation to become continuous 

 with the malleus. The body of the mandible diminishes gradually toward the symphysis. It 

 has the form of a trough enclosing the large dental gutter, which begins immediately distad of 

 the coronoid process. 



Hyoid. The hyoid is well ossified and shows no sutures between its component parts. 

 The lesser cornua point directly rostrad and are separated by a deep and narrow notch. To their 

 apices are attached the strong and rounded stylohyoid ligaments, which run dorsad to the 

 extremities of the stylohyals. The greater cornua are of large size, extending laterad and 

 slightly dorsad; between their extremities the caudal border of the bone is transverse, and 



