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Show 236 ON THE CETACEAN GENUS MESOPLODON. [Feb. 28, EXPLANATION OF THE PLATES. PLATE XII. Fig. 1. Upper surface of cranium of Mesoplodon grayi, Haast, type, J nat. size. 1 a & 1 b. Transverse sections of the rostrum of the same at a and b respectively, nat. size. 2. Outline transverse section of M. haasti, Flower, after Flower, for comparison with the sections la and 16, nat. size. PLATE XIII. Fig. 1. Upper surface of cranium of Mesoplodon grayi, Haast-the Kaiapoi skull (I), \ nat. size. 1 a & 1 b. Transverse sections of the rostrum of the same at a and b respectively, nat. size. 2. Outline transverse section of M. australis, Flower, after Flower, for comparison with the sections 1 a and 1 b, nat. size. PLATE XIV. Fig. 1. Transverse section of rostrum of Ziphius cavirostris. $ • 2a & 2b. Transverse sections of the rostrum of a young individual of Mesoplodon grayi, Haast. Cf. fig. 1, page 221. 3. Outline transverse section of the rostrum of M. grayi, Haast, in the E. Coll. Surgeons, alter Flower. 4 a & 4 b. Transverse sections of the rostrum of M. grayi, Haast, £ > m Canterbury Mus., Christchurch, N.Z. 5. Transverse section of the rostrum of M. grayi, Haast, $, in the Otago Lniv. Museum, N.Z. Fig. I is # nat. size; figs. 2-5 nat. size. PLATE XV. Figs. 1, 2. Transverse sections of Mesoplodon grayi, Haast-Specimen E in list above, from the Chatham Islands, nat. size. 3-5. Transverse sections of M. grayi, Haast-G- in the list above, from the Chatham Islands ; fig. 4 is tbe most anterior and 5 the most posterior section, and all are of the nat. size. EXPLANATION OF ABBREVIATIONS. br.g. Basirostral groove. butt. Maxillary buttress. gib. Gibbosity. mr. Mesorostral bone. mr.s. „ suture. mr.cr. ,, crease. mx. Maxillary bone. mx.f. „ foramen. mx.i. „ ingrowth. meth. Mesethmoid bone. meth.s. Anterior termination of mesethmoid bone. pmx. Premaxillary bone. pmx.s. „ suture. pmx.o. „ ossification. pmxf. „ foramen. s.oc. Supraoccipital bone. v. Vomer. v.s. Vomerine suture. v.tr. „ trough. |