142 



pital posteiiorly and laterally as far as tlie zygomatic arch, which 

 is by no means the case in the AUactagas, where all the osseous parts 

 of the ear are of moderate dimensions. Another difFerential character 

 between the two genera, is presented by the maxillary arch, W'hich 

 circumscribes extemally the suborbital foramina, and which, in the 

 AUactagas, may be said to be linear, and presenting a very limited 

 surface for the attachment of museles. Lastly, we may note a dif- 

 ference in the relative development of the jaws, the lovver being com- 

 paratively mucli shorter in the AUactagas than in the Jerboas." 



The author then proceeds to describe a new species of AUactaga, 

 a native of Barbary, for which he proposes the name of ^. arundinis. 

 Its length from the origin of the tail to the end of the muzzle, 5 inches ; 

 length of the tail, o inches and 2 or 3 lines; of the ears, 1 inch; length 

 of the tarsi from the heel to the extremity of the toes, 22 lines. All 

 the upper parts of the body are of a beautiful greyish yellow, M'ith 

 yellowish sides and tail of the šame colour, terminated by a tuft of a 

 blackish brown at its origin, and -vvhite at the extremity. The sides 

 of the cheek, the ventral surface of the body, and the intemal limbs 

 are white; large brov/n moustaches adom the sides of-the muzzle. 

 The incisors are \vhite and entire, the ears almost naked. 



M. Cuvier next proceeds to eonsider the characters and affinities 

 of the genera GerbiUtts and Meriones, and enters into a critical ex- 

 amination of all the species referred to that group. To these he adds 

 another species, the habits of which he details, and describes at length 

 under the name of G. Burtoni. ^Tie species wliich he thus includes 

 are, Ist, G. Egyptiacus, syn. Dipus GerbiUtts, Meriones cuadrinia- 

 CM?a^Ms, Ehrenberg ; 2nd, GerbUlus pyramidum, syn. Dipus pyramidvm 

 Geoff., Meriones 7-obustus ^upp. ; 3rd, G. pi/gargus, syn. Meriones 

 Gerbilhts, Rupp. ; 4th, G. Nidicus, syn. Dipus Nidicus, Hardwicke ; 

 5th, G. Africanus, syn. Meriones SchlegeUi Smutz., G. Afra Gray ; 

 6th, G. hrevi-caudatus ; 7th, G. Ofaria ; 8th, G. Burtoni. The author 

 enters into detailed descriptions of each of these species from original 

 specimens. M. Cuvier lastly considers the affinities of the Gerbillas 

 and AUactagas to the Gerboas, and concludes that the GerbiUas have 

 a much nearer affinity to the Murida. 



Mr. Gould exhibited to the Meeting all the species from ^hich the 

 dravvings had been taken for the first part of his ne\v work on the 

 Birds of Australia, among which were several new and very remark- 

 able forms. The following hitherto undescribed genera and species 

 \vere named and characterized. 



OcYPTERUs suPERCiLiosrs. Oc.facie, guld, pectoreque nigrescenti- 

 griseis ; Uaed superciUari albd ad basin rostri excurreiite ; summo 

 capite, corpore superiore alisque fuūginosis ; abdomine crissogtte 

 castaneis ; rectricibus griseo-fuUginosis, ad apicem albescentibus, 

 intcrmediis daabus e.vceptis ; ?oslro plumbeo, ad apicem nigro ; 

 pedibus plumbeis. 



Long. tot. 7 unc. ; rostri, 1 ; alee, 4į ; caud<e, 3 ; tarsi, ■^. 



Hnb. In Nova Cambria Australi. 



