“The greatest peculiarity is in the form of the lumbar and anterior caudal vertebræ; they are of a much more elongate form than any I have seen or found figured, excepting those of the _Balænoptera rostrata_ (as figured by Gaimard in ‘Voyage de la Recherche’), which, however, are relatively shorter. Those of the present species are of greater length than transverse diameter, the lumbars most elongate; all furnished with an acute hypapophysial keel and concave sides, and entirely transverse diapophyses. This peculiarity is consistent with the account of my informant, who stated the animal to have been of an unusually elongate and slender form. When it came ashore it had perhaps been dead ten days; the flukes and muscular region as far as the third caudal vertebra had been devoured, probably by Sharks and Killers, and the abdominal region much lacerated; the edge of a fin preserved was slit by the teeth of some carnivorous enemy. The measurement from the end of the muzzle to the end of the third caudal was 35 feet, which may be reduced to 33 feet axial. Up to this point the dorsal line was, according to my informant, entirely smooth, without knob or fin, or scar of one; hence I suppose the fin (if present) to have been situated, as in _Sibbaldius_ &c., at the posterior fourth of the length, and not, as in _Balænoptera_, on the posterior third. It may then be safely assumed, bearing in mind the form of vertebræ, that ten feet of the whale’s length had been removed, making in all 43 feet. That the species attains over 50 feet is probable, as the present individual was quite young, the epiphyses separating from the vertebræ with the greatest ease. The slender form of the animal is corroborated by the slenderness and slight curvature of the ribs, one attached beneath the scapula, probably the second, being narrower than the corresponding ones in _Sibbaldius_. I therefore think it most probable that in this form the anterior ribs are single-headed.”—_Cope_, _l. c._ p. 223. 1. Agaphelus gibbosus. _The Scrag Whale._ Agaphelus gibbosus, _Cope_. Balæna gibbosa, _Gray_, _Cat. Seals & Whales_, p. 90. Scrag Whale, _Dudley_, _Phil. Trans._ xxxiii. p. 259. Inhab. North Atlantic. 2. RHACHIANECTES. Rhachianectes, _Cope_, _Proc. Acad. N. Sc. Philad._ 1869, pp. 14 & 15. Cervical vertebræ free. Throat without plaits. Dorsal fin none. Scapula without acromion. 1. Rhachianectes glaucus. _The Californian Grey Whale._ Rhachianectes glaucus, _Cope_, _Proc. Acad. N. Sc. Philad._ 1869, pp. 17 & 40, fig. 8. Agaphelus glaucus, _Cope_, _ibid._ 1868, p. 225. Inhab. California, San Francisco. “The points in which this species differs from those of the genus _Balæna_ previously known are numerous, and will no doubt be increased on a further knowledge of the animal.