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Show 978 DR. C I. FORSYTH MAJOR ON A [Dec. 1, the frontal joins the maxillary, thus separating the lachrymal and nasal; and, besides, there is such a variability in the size and mutual connections of the bones in this part of the skull in young specimens, and, to a certain extent, in adult ones as well (four nasals, obliteration of the Jachrymo-frontal suture, & c ) , that we cannot here enter into more particulars. M y purpose was to show that, in respect of the above characters also the Malagasy Hippopotami are intermediate between H. sivalensls and H. amphiblus, and appear to be in close relationship with both. Occasionally young specimens are hexaprotodont, as the Siwalik forms. I think that, from what I have stated, we are fairly entitled to surmise that the Hippopotami entered Africa at a time when they were still in possession of all the characters of the Shwalik species, and that they crossed over to Madagascar when they had reached a condition intermediate between H. sivalensls and H. amphiblus. In this condition they persisted in Madagascar, whilst on the neighbouring continent they progressed (or retrogressed) farther in the same direction. It is a curious circumstance that the Hippopotamus major from the Upper Pliocene of Italy has gone beyond H. amphiblus in the same specialization; this may have had something to do with its earlier extinction. RODENTIA. But little attention has hitherto been paid to the Rodent fauna of Madagascar. Although four or five more or less nominal genera had been founded, it has been surmised that the Malagasy Rodentia have immigrated in recent times and are not even specifically Madagascar genera. This supposition rests on the assumption that the Rodents are, as a rule, passively wandering (Wallace, Zittel), and was made in spite of Peters having long ago pointed out that Nesomys, the first known Malagasy Rodent, resembles tbe American Hesperomyes in the conformation of the enamel and in the proportions of its molars 1. M y collections contain some hundred specimens of Rodentia, belonging to five genera and eight species, five or six of tbe species and two genera being new, besides two new genera found in a fossil condition. This material I have begun to work out, and, although m y investigations are far from being completed, I do not think that the following conclusions will hereafter have to be modified in their main points. The great majority of Malagasy Rodents at present known, viz. the genera Nesomys, Hallomys, Gymnuromys, Ellurus, Brachy- 1 " Eine neue Gattung der Murinen aus Madagascar, -welchein dem Zahnbau sich am naehsten den Hesperomys der westlicben Heniisphare anschliesst, und so ein neues Beispiel von der geographisch so merkwiirdigen Verwandtschaft der Fauna von Madagascar mit der von Amerika liefert Die Backzahne 3-3, in ibrer Scbmelz bildung und Proportion ahnlich denen von Hesperomys." (Sitzungsber. Ges. naturf. Freunde Berlin, Oct. 18, 1870, pp. 54, 55.) |
