[a] Curvilinear. [b] Straight. [c] To anterior base. [d] Lower jaw to “beginning of pectoral.” [e] From tip of upper jaw. [f] From tip of lower jaw. [g] Points of measurements not specified. [h] From the bones; from outer anterior margin of proximal expansion of ulna. [i] Along center. [j] From the bones. The external measurement originally taken by Scollick is entirely too large. [k] The skull gives this measurement as 10.4 per cent. The original measurement by Scollick is entirely too large and can not be correct. The same is probably true regarding length to blowhole, but I can not prove it. The close correspondence in proportions shown in this table favors the idea of specific identity, and taken with the similarity in size, and characters of the skull, warrants, I think, the assumption that the specimens from the Atlantic coast of the United States belong to _Z. cavirostris_. COLORATION. It should be remarked, however, that the Barnegat City specimen does not agree in color with any of the European or New Zealand specimens. On the other hand, the latter show a most extraordinary diversity in color, some being black, with the head and back as far as the dorsal fin white; others all black above, white below, and the head black and brown. The color of the young specimen from Buenos Ayres, Argentina, is described by Burmeister as follows: All the body of the animal is of a light gray color, a little yellowish, resembling the color of light ash, but much darker on the back and much lighter on the belly. The fins are much darker than the back—almost black—and the large fin of the tail has a very pure white area of irregular shape on the underside. If the indications from the skull and proportions are trustworthy _Z. cavirostris_ must be a species in which the color is very variable, differing perhaps in the two sexes, or with differences in age. This is, however, by no means certain at present, and whether the diversities of color reported in different specimens are merely individual variations, or are due to post-mortem changes, remains to be discovered. It will be noticed that the color of the Argentine specimen is nearest to that of the Barnegat City specimen. TYPE OF ZIPHIUS SEMIJUNCTUS (COPE).