Mr. Waterhouse on ntw Rodenlia. 445 



family, including Meliphaga tenuirostris of authors. For this new 

 group he proposed the generic title of Acanthorhynchus, and for the 

 two new species the names of A. superciliosus and A. dubius. 



Acanthorhynchus. (Gen. char.) Rostrum elongatum gracile et 

 acutum ; ad latera compressum ; tomiis incurvatis ; culraine acuto 

 et elevato. 



Nares basales elongatse et operculo tectae. 



Lingua ut in Gen. Meliphaga. 



Alee mediocres et sub-rotundatse, remigibus primis et quintis fer^ 

 sequalibus ; tertiis et quartis intense aequalibus et longissimis. 



Cauda mediocris, et paululiim furcata. 



Tarsi elongati, fortes ; halluce digito medio longiore et robustiore ; 

 digito externo medium superante. 



Ungues curvati. 



Typus, Certhia tenuirostris, auct. 



The following species, also in Mr. Gould's collection, were named 

 and characterized ; viz. 



Pardalotus affinis, Nanodes elegans, Platycercvs Jlaveolus, and 

 HiMANTOPUs leucocephalus. 



Mr. Gould also characterized under the following names two new 

 species of the genus Stertia, from the collection in King's College, a 

 species oi Cormorant in the United Service Museum, and three spe- 

 cies of the genus Orpheus, from the Galapagos, in the collection of 

 Mr. Darwin. 



Sterna poliocerca and Stern, macrotarsa; Phalacrocorax bre- 

 virostris ; and Orpheus trifasciatus, 0. melanotis and 0. parvulus. 



Mr. Waterhouse resumed the exhibition of the small Rodents, 

 belonging to the collection 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 external form, 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. Like 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- 

 ternally in each. In the front molar of the lower jaw the enamel 

 enters the body of the tooth three times internally, and twice ex- 

 ternally. 



As the above-mentioned characters, in Mr. Waterhouse's opinion, 

 evidently indicated an aberrant form of the Muridae, he suggested 



