| OCR Text |
Show 1870.] MR. J. B. PERRIN ON BALAENOPTERA ROSTRATA. 807 animal, which was still further increased by the ribbed arrangement of the skin on the anterior half of the ventral aspect. This ribbed arrangement was produced by numerous longitudinal furrows or sulci, which penetrated fully a quarter of an inch in depth into the skin, and ran in a more or less regularly parallel manner from before backwards, thus dividing the integument into striae. These strise were limited laterally by a line drawn from the angle of reflection of the jaws to the base of the flippers, in which situation they were short and somewhat arched. The striae commenced in front at the lower jaw, extending its whole length. They were wider both at their commencement and at their termination than in the rest of their course. The median striae were smaller than the lateral, and more uniform in width throughout their entire length, measuring about half an inch, and sometimes a little more or less; whereas the lateral striae at origin and termination measured from 14; to i\ inch. Posteriorly they terminated in a radiate manner, those in the middle line of the ventral surface being the longest, the remainder gradually shortening as they approached the lateral aspect of the trunk. The sulci or grooves in the median line presented some difference from those more laterally situated. Thus the former terminated more gradually than the latter, and resembled a cut made into the skin by an inexperienced operator; the lateral sulci terminated sharp and abruptly. These plicae or folds did not decussate, or decrease in number in their transit from before backwards, as mentioned in Carte and Macalister's specimen ; they were continuous and well marked throughout. The sulci were wedge-shaped, and not quadrilateral as shown diagrammatically by Hunter; no doubt, if the integument were considerably distended they would present that appearance. The flipper was traversed about the middle of its entire circumference by a zone of white, which contrasted strongly with the slaty black which extended along its basal extremity for about eight inches, and for the same distance along its distal end. This white zone at tbe basal end was limited by a sharp and abrupt line of termination directed obliquely from before backwards. Distally it terminated in a radiate manner, the white becoming gradually lost in the black. The ventral surface of the tail was likewise covered with white integument, except at the margins, where the white and black gradually merged into each other. The Cranio-mandibular Articulation.-This articulation presented several remarkable and interesting features. It was effected by means of a huge fibro-elastic mass, spheroidal in shape and closely adherent by both of its extremities to the squamosal posteriorly, and the condyle of the mandible anteriorly. A small portion, however, of the concavity of the squamosal was free, the cartilage being unattached, as ascertained by making an artificial opening ; the finger could be readily passed for a short distance underneath. There was not the slightest trace of a synovial membrane even here; and tbe close adherence of the elastic mass to the rest of the squamosal, on the one hand, and the globular head of the mandibular arch on PROC. ZOOL. Soc-1870, No, LIV. |
