1882.] ON THE ANATOMY OF ERETHIZON DORSATUS. 271 



the possession of powder-down patches, in the oil-gland being nude 

 (IMesites), and in the interruption of the dorsal tract in the neighbour- 

 hood of the scapulae. Pterylographically, therefore, there is no special 

 reason to unite these forms with the Rails. Judging from M. Milne- 

 Edwards's account and figures of the osteology of Mesites, numerous 

 differences between these two forms also exist in the osseous parts 

 of their structure. lu particular, the fact of Mesites being schi- 

 zorhiual is a strong point in view of its relationship being, along with 

 Rh'mochetus and its allies, to the PluviaUne group, where I have 

 already ^ placed it. In spite of M. Milne-Edwards' s remarks ", I 

 see no reason for doubting the value of the schizorhinal character of 

 the nasal bones as a mark of the genetic affinities of birds, especially 

 when, as in the present case, other facts point in the same direction. 

 I should be inclined therefore to consider (I) that Mesites, 

 JEurypijga, and Rhinochetus have all sprung from some common 

 ancestor, which must have been a generalized Pluvialine form pro- 

 vided with powder-down tracts ; (2) that of the forms which this 

 common stock gave rise to, all have become extinct save the three 

 in question, which, having become isolated in three widely separated 

 localities, have each acquired certain special characters not found in 

 the others ; (3) that, judging at least from the pterylosis, the 

 Malagash Mesites is perhaps more nearly related to the New-Cale- 

 donian Rhinochetus than to the Neotropical Eurypyga. 



5. Notes on the Anatomy of Erethizon dorsatus. 

 By St. -George Mivart. 



[Eeceived February 16, 1882.] 



Having had an opportunity, through the kindness of Dr. Giinther, 

 of examining a spirit-specimen of Erethizon dorsatus, the following 

 points have appeared to me possibly of some interest. 



The tongue is long and narrow, its extreme length being 4"*7 and 

 its greatest breadth (at its hindmost end) being 1"*4 ; close to the tip 

 it is only -5 (cent.)^ Its hinder margin has a deep median notch. The 

 intermolar eminence is considerable. There is no median groove on 

 the dorsal surface ; and there are but two oval and rather large cir- 

 cumvallate papiilfe at the hinder margin of the tongue. The long 

 axes of these two papillae diverge forwards and outwards. The sur- 

 face of the dorsum of the tongue is, for its anterior half, covered 



• Ibis, 1881, p. 4, and P. Z. S. 1881, p. 644. 



^ The greater or lesser size of the beak will not account for the schizorhinal 

 or holorhmal character of the uares, as suggested by M. MUne-Edwards. Else 

 why should the big-billed Plaialea, Ibises, Bidimculm, LaridcB, Alcidce, be all 

 schizorhinal, whilst the slender-billed Bails, Colymbidce, and such Tubmares as 

 Puffinus and Procellaria, to say nothing of such forme as the MeropidcB, Dendro- 

 colaptidcB, and Nectariniid<B, are all equally holorhinal ? Nor can I "admit with 

 M. Milne-Edwards that the Pteroclidai are related to the GallincB, or the Ibididce 

 to Tantalus, there being plenty of collateral evidence to prove the reverse. Hence 

 any argument based on such assiuned affinities also fails. 



In this paper aU the measurements are in centimetres, except where other- 

 wise expressed. 



