PEOFESSOE FLO WEE ON THE EECENT ZIPHIOID WHALES. 209 



on the sides of the nares to the vertex, where they are dilated laterally, the right one 

 especially, the outer edges curving backwards, their anterior surface arching forwards 

 above, overhanging the nares. Nasals lying, more or less sunken, in a hollow between 

 the upper ends of the prsemaxillse ; their anterior surface more or less concave, not 

 projecting so far forward as the upper part of the prsemaxillae, and not separated on 

 each side from those bones by a distinct notch. Anteorbital notch not very distinct. 

 Rostrum long and narrow. No maxillary tuberosities. Mesethmoid generally ossified 

 in its entire length, and coalescing with the surrounding bones. 



A much compressed pointed tooth in each ramus of the mandible, variously situated, 

 but generally at some distance behind the apex ; its point directed upwards, and often 

 somewhat backwards, occasionally developed to a great size (in the males 1). 



Dictionnaire d'Histoire Katurelle,' 2nd edit. Paris, 1817, the subgenus Heterodon comprises eight species, 

 of which five (B. groenlandicus, cheinnitzianus, edentitttis, bidenttitus, and butskode) arc synonyms of Hyperoodon 

 rostra tus, one (D. epiodon) an ill-described species from the Mediterranean, perhaps a true Ziphius, and two 

 (B. sowerbensis and B. densirostris), undoubtedly belong to the section at present under consideration, being 

 founded on the only specimens at that time known to naturalists. It is clear, therefore, that Blainville's 

 Heterodon is equivalent to the present section, plus Hyperoodon ; and the latter being removed, the name might 

 very well have been retained for the remainder, if it had not been previously in use for a genus of snakes. 

 Heterodon is employed in the same sense as by De Blainville for a subgenus in Desmarest's ' Mammalogie,' pt. 2. 

 1822, and as a genus in Lesson's ' Manuel de Mammalogie,' 1827. The specimen taken at Havre in 1825, 

 apparently a female of Sowerby's Dolphin, supposed by its first describer, De Blainville, to be of the same 

 species as the Dolphin described by Dale (now considered a Hyperoodon), was named by Cuvier Belphinus 

 micropteriis, and forms the type of the genus Beljihinorhynchus of F. Cuvier's ' Histoire des CetaceV (1836), 

 being associated with several other Dolphins of very different structure and even belonging to different families. 

 But Delphinorhynchus had been previously used by Blainville, in the article above cited, for a heterogeneous 

 group of Dolphins, among which none of the present genus appears ; so that it is perfectly inadmissible. The 

 term Biodon, proposed by Lesson for the male, was already in general use for a genus of fish. Aodon (Lesson, 

 Compl. de Buffon), changed to Nodus (Wagler, Syst. de Amph. 1830), likewise proposed for the female, being 

 positively erroneous in signification, have never been generally received. Wagner (Schreber, Supplement, 

 p. 352, 1846) constituted Mieropterus as a subgenus of Belphinus, for the then known animals of the group, 

 uniting them into a single species, but overlooking the fact that the name had already been given to more than 

 one genus in the animal kingdom. Eschricht, however, adopted it in a generic sense (Nordische Wallthiere, 

 p. 50, 1849), altering the spelling to Micropteron, in which form it has been used by Huxley (Proc. Geol. Soc. 

 1864, p. 388). In 1850 Gervais (Annales des Sciences Naturelles, 3 e ser. torn, xiv.) divided the group (as 

 defined above), though, as appears to me, on very insufficient grounds, into two genera, which he named 

 Mesoplodon and Bioplodon, Blainville's Heterodon sowerbensis being the type of the one, and his H. densirostris 

 the type of the other. In the following year Duvernoy, in a memoir in the same journal, reunited them, 

 bestowing the name of Mesodiodon on the whole group. Subsequently Fischer (Nouv. Archives du Museum, 

 iii. 1867, p. 67), not recognizing Gervais's divisions, adopted his name Mesoplodon for the entire genus, in 

 which I have followed him. Owen, as above mentioned, includes this group, with all the rest of the subfamily, 

 except Hyperoodon, in the Cuvierian genus Ziphius (Crag Cetacea, Palaeont. Soc. vol. xxiii.), while Gray 

 (Suppl. Cat. Seals and Whales in Brit. Mus. 1871) divides it into Ziphius, Bolichodon, Neoziphius, and Bio- 

 plodon, which, with Berardius, constitute the family Ziphiidae — the type of Cuvier's Ziphius being placed, 

 under the name of Petrorhynchus mediterraneus, in a different family. 



