106 EINAR LONNBEEG, MAMMALS COLLECTED BY THE SWEDISH ZOOLOGICAL EXPEDITION ETC. 



galeata-gvou^ with long nasals which as a rule have a great relative breadth also in 

 front, and the southern africce-australis-gromp with shorter nasals which are much 

 narrower in front than behind. 



The Porcupines obtained by this Expedition belong, as could be expected, to 

 the former group and to Hystrix galeata, which species, however, has been subdivided 

 into some geographical subspecies by the present writer^ and Ferd. Muller.^ Of 

 these subspecies H. g. ambigua Lonnberg is easily recognized on the shape and 

 proportions of its nasals, the breadth of which at the front end of the nasopremaxil- 

 lary suture is only 57 "/o of their breadth at the posterior end of the same suture etc. 



Ferd. Muller has named not less than three new subspecies of H. galeata. 

 In doing so he lays great stress on the fact that the skull of the type of H. 

 galeata Thomas (which was a young or semiadult specimen in which the last molar 

 is not yet in use) has greater posterior interorbital width (at rudimentary postorbital 

 processes) than anterior interorbital width (at edge of lacrymals). Muller regards 

 this as such a valuable characteristic that he divides the subspecies of H. galeata 

 »in 2 Gruppen* — — »einmal in solche, deren grosste Frontalbreite hinten, an dem 

 rudimentaren processus postorbitalis liegt, und sodann in solche bei denen die Breite 

 der Frontalia vorne, an der Wurzel des Lacrymale, am grossten ist. » To the first 

 group belongs (the type of) Hystrix galeata Ttlom. as, to the second the already men- 

 tioned H. g. ambigua, and Muller's ^H. g. conradsi^, »H. g. lademanni^, and »i/. g. 

 lonnbergii. Concerning the three latter not much information is given. H. g. con- 

 radsi is said to have the width of processus nasalis prsemaxillaris 12 — 14 mm., and 

 the thickness of arcus zygomaticus maxillaris 3,5 — 4 mm., while the corresponding 

 measurements of H. g. lademanni are 16 — 16,5 and 7 mm. respectively. With regard 

 to H. g. lonnbergi the reader obtains no other information than about those points 

 by which it differs from H. g. ambigua, but not how it is to be distinguished from 

 H. g. conradsi, and H. g. lademanni, while the difference from the typical H. galeata 

 shall consist in the anterior interorbital breadth being smaller than the posterior. 



The question is now whether these interorbital measurements and the relation 

 between them is constant or not? That the interorbital measurements themselves 

 are not constant is easily ascertained by examination of some Hystrix galeata-skuWs 

 of different age. It appears also almost certain that the anterior interorbital width 

 increases more with age than the posterior to judge from the general development 

 of the skulls. In two specimens from Kilimanjaro, for instance, the anterior measure- 

 ment is in the younger 69 mm. and in the older 75 mm. while the posterior mea- 

 surements are resp. 67,7 and 71,5 mm. The difference between the two dimensions 

 is thus in the younger only 1,3 mm. but in the older 3,5 mm.' I appears therefore 

 probable that in still younger skulls this difference may -decrease still more, or even 

 be inverted. 



The variability of these dimensions has also been very plainly proved by Ferd. 



Muller himself concerning the by him described H. stegm.anni.^ The difference 



^ MammaJs. Schwed. Zool. Exp. nach dem Kilimandjaro und Meru. Upsala 1908, p. 29. 

 ^ Sitzber. Ges. Naturforsch. Freunde. Berlin 1910 p. 314 — 315. 

 ' Arch. f. Naturgesch. 76 Jahrg. 1910. Bd. I, p. 182. 



