“There is a skeleton of the _Balæna cisarctica_ in the Museum of the Academy of an individual of 37 feet, and a ramus mandibuli 16 feet in length, indicating a total of 68 feet, adult size. A scapula in the Museum, Rutger’s College, New Brunswick, N. J., measures 36 inches in height, and 48·5 inches in width, indicating an adult of 57 feet in length. A young individual of 45 feet, line-measurement, awaits mounting in the Museum Compar. Zoology, Cambridge, Mass. Of this individual I will shortly give a detailed description in an essay on the species. Like the other specimens, it presents a strong acromion. The phalanges of the manus exhibited an important difference from those of _B. australis_. In it they number respectively 2, 5, 6, 3, 3, while Cuvier gives (Oss. Foss. 227. 23) 2, 5, 6, 5, 4.” 4. HUNTERIUS. Hunterius, _Gray_, _l. c._ pp. 78, 98; _Synops. Whales & Dolph._ p. 1; _Lilljeborg_, _N. Acta Upsal._ vi. 1867. First rib broad, with a double head at the vertebral end. Tympanic bones square; aperture nearly as long as the bone. Vertebræ 57 or 58; the five first cervical united. Five phalanges in the fourth or ring finger, and four to the second, third, and fifth fingers. The first rib bifid and articulated to the first two dorsals, or the last cervical and the first dorsal; the second rib very thick at the free end. The nasal bones very large. 1. Hunterius Temminckii. Hunterius Temminckii, _Gray_, _l. c._ p. 98, fig. 8; _Synops. Whales & Dolph._ p. 1; _Ann. & Mag. N. H._ 1870, p. 191. Balæna australis, _Temm._ _F. Japon._ t. 28, 29. Balæna australis, var., _Van Ben._ _Ostéogr. Cét._ p. 35. Inhab. Cape of Good Hope. M. van Beneden regards the character on which this genus is established as merely a variation of _Balæna australis_ (Ostéog. Cét. p. 35). The skeleton was sent from the Cape of Good Hope by Dr. Horstock. It is described by Schlegel, Abhand. Gebiete der Zool. 1841, p. 37 (Flower, P. Z. S. 1864). 2. Hunterius biscayensis. Hunterius biscayensis, _Gray_, _Ann. & Mag. Nat. Hist._ 1868, i. p. 244; _Synops. Whales & Dolph._ p. 2. Balæna biscayensis, _Eschricht_, _Compt. Rendus_, 1860, _Act. Soc. Linn. Bordeaux_, xiii.; _Gray_, _Ann. & Mag. N. H._ 1870, p. 200 (not _Van Beneden_). Balæna eubalæna, _Flower_, _P. Z. S._ 1864, p. 391. Inhab. St. Sebastian. Skeleton of very young animal in Mus. Copenhagen, from the Museum of Pampeluna. Mr. Flower informs me that this skeleton belongs to the genus _Hunterius_, which has brittle whalebone, with a large coarse fringe (which easily splits into strips), and a bifid first rib. 3. Hunterius Swedenborgii. Hunterius Swedenborgii, _Lilljeborg_, _N. Act. A. Sci. Upsal._ vi. 1867, p. 35, t. 9, 10, 11 (skeleton); _Gray_, _Synops. Whales & Dolph._ p. 1. Inhab. North Sea; Sweden (subfossil). 5. CAPEREA.