PROFESSOR FLOWER ON THE RECENT 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 premaxille; their anterior surface more or less concave, not 
projecting so far forward as the upper part of the premaxille, 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 2). 
Dictionnaire d'Histoire Naturelle,’ 2nd edit. Paris, 1817, the subgenus Heterodon comprises eight species, 
of which five (D. grenlandicus, chemnitzianus, edentatus, bidentatus, and butskode) are synonyms of H ‘yperoodon 
rostratus, one (D. epiodon) an ill-described species from the Mediterranean, perhaps a true Ziphius, and two 
(D. sowerbensis and D. 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 Blainyille’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 Blainyille 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 Blainyille, to be of the same 
species as the Dolphin described by Dale (now considered a Hyperoodon), was named by Cuvier Delphinus 
micropterus, and forms the type of the genus Delphinorhynchus of F. Cuvier’s ‘ Histoire des Cétacés’ (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 Diodon, 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 Micropterus as a subgenus of Delphinus, 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° sér. tom. xiy.) divided the group (as 
defined above), though, as appears to me, on very insufficient grounds, into two genera, which he named 
Mesoplodon and Dioplodon, Blainyille’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 (Nouy. Archives du Muséum, 
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, Palxont. Soc. vol. Xxiil.), while Gray 
(Suppl. Cat. Seals and Whales in Brit. Mus. 1871) divides it into Ziphius, Dolichodon, Neoziphius, and Dio- 
plodon, which, with Berardius, constitute the family Ziphiidee—the type of Cuyier’s Ziphius being placed, 
under the name of Petrorhynchus mediterraneus, in a different family. 
