27 



nigris; dorsi alarumgtie plumis intensė cinereis, nigro margina- 

 tis, pedibus nigris. 

 Long. tot. 23 unc. ; rostri, 2f ; alte, 9į^; cauda, 7^; tarsi, lį. 



Orpheus trifasciatus. Orph. vertice, nuchd, et dorso nigres- 

 centibus; uropygio rufopallidė lavato; alis nigrescentibus tectri- 

 cibus nota cdbescente terminali, fascias tres transversas facienti- 

 bus rectricibus caudcB duabus intermediis nigrescentibus, religuis 

 ad apicem pallidioribus ; plumis atcricularibus strigd superci- 

 liari, gidd, et corpore subtits albis, lateribus riotis gtUtisgue 

 fuscis ornatis ; rostro pedibusgue nigris. 



Long. tot. 10^- unc. ; rostri, \į ; alcE, 5 ; caudce, 5| ; tarsi, lį. 



Orpheus melanotis. Orph. vertice, nuchd, dorsogue pallidi fus- 

 cis ; plumis capilis et dorsi ad medium colore saturatiore ; alis 

 intense fuscis sinyulis, plumis ad marginėm pallidioribus, seconda- 

 riis, tectricibusque majoribus notd albd terminali, fascias duas 

 transversas facientibus ; caudce rectricibus nigrescenti-fuscis ad 

 apicem albis, loro, plumisąue auricularibus nigrescenti-fuscis ; 

 laterum plumis notd fuscd centrali, abdomine albo ; rostro pedi- 

 busque nigris. 



Long. tot. 9| unc. ; rostri, lį ; al<B, Ą\ ; caudee, 4§ ; tarsi, If . 



Orpheus parvulus. Orph. vertice, nuchd cauddgue intensė fuscis, 

 hujus rectricibus ad apicem albo notatis; alis fuscis secondariis 

 tectricibusgue notd albd apicali fascias duas transversas facien- 

 tibus ; loro, plumisgue auricularibus nigrescentibus, guld, colli 

 lateribus pectore, et abdomitie albescentibus ; plumis laterum notis 

 fuscis per medium longitiidinaliter ezcurrentibus. 



Long. tot. 8^ unc. ; rostri, 1 ; al(B, 3§ ; caudce, 3f ; tarsi, lį. 



Mr. Waterhouse resumed the exhibition of the small Rodents, 

 belonging to the coUection presented by Mr. Darwin to the Society. 

 Among them were three species allied to the genus Mus, but offering 

 some slight modification, not only in the extemal fonu, but in the 

 structure of the teeth. They have the fur soft and silky ; the head 

 large, and the fore legs very small and delicate ; the tarsus mode- 

 rately long and bare beneath ; in the number and proportion of the 

 toes they agree with the true rats ; the tail is moderately long, and 

 more thickly clothed with hair than in the typical rats. The ears 

 are large, and clothed with hair. Likę the true rats, they have 

 twelve rooted molars ; the folds of enamel, however, penetrate 

 more deeply into the body of each tooth, and enter in such a way 

 that the crowns of the teeth are divided into transverse and some- 

 what lozenge-shaped lobes, or in some instances into lobes of a 

 triangular form. In the front molar of the upper jaw the enamel 

 enters the body of the tooth twice, both on the outer and inner 

 sides ; and in the second and posterior molars, both of the upper 

 and under jaws, the enamel penetrates but once externally and in- 



