The foregoing differences amount to this: That in _B. bairdii_ the commencement of the lower series of transverse processes is pushed back one vertebra, as compared with _B. arnuxii_, and that in the ninth thoracic of the former species, which corresponds to the eighth of the latter species, the metapophysis has a short process on the side for the articulation of the tubercle of the rib, instead of merely a sessile facet. Although in other genera of ziphioids these differences would perhaps be looked upon as individual, since they are constant here they may be considered specific, at least provisionally. SCAPULA. In _B. bairdii_ the anterior border of the scapula is narrower than in _B. arnuxii_, the anterior ridge coming close to it and lying parallel with it. The acromion is directed more upward, so that the angle between it and the body of the scapula is more acute, and the process itself is rather more expanded distally. The coronoid is inclined a little more downward. The whole surface of the scapula is very uneven. (Pl. 33, fig. 2.) HUMERUS AND ULNA. The humerus is shorter than in _B. arnuxii_ and broader distally, and much more recurved on the ulnar side. The ulna is much broader distally and its whole shape is different. (Pl. 33, figs. 3 and 4.) CHEVRONS. As the skeleton of the typical form _arnuxii_ has been described in considerable detail and accurately figured by Flower and by Van Beneden and Gervais, it is not considered necessary to give a complete description of that of _bairdii_ in this place. The entire skeleton and many of the separate bones are figured in Pls. 42, 32, and 33. The phalanges are lacking altogether, or are incompletely represented, in the various skeletons of _bairdii_, and for that reason the phalangeal formula can not be given. The chevrons number ten in the skeleton from Centerville beach, California (Cat. No. 49725). Both Flower and Van Beneden and Gervais give nine chevrons as the number for the skeleton of _arnuxii_ in the Hunterian Museum, London, but the latter authors have added a tenth in outline in the figure of the skeleton of that species which is in the Paris Museum. Ten are mentioned by Hector as the correct number for the skeleton of _arnuxii_ from Wellington Harbor examined by him.[61] STERNUM. The sternum of _bairdii_ (Pl. 32, fig. 2) consists of five segments and does not offer characters by which to distinguish it from that of _arnuxii_. In the former species the first eight pairs of ribs possess distinct heads and tubercles; the tubercle is rudimentary in the ninth pair and absent in the tenth and eleventh. The dimensions of the three skeletons of _bairdii_ and of that of _arnuxii_ described by Flower are as follows: _Dimensions of one skeleton of Berardius arnuxii and three skeletons of B. bairdii._