On (he Baculum of some Genera of Mustelidae. 307 



name. But that lie later realized its peculiarity is proved 

 by his having written on the typical skin a special generic 

 name, no doubt intended for ultimate publication. 



4. Nesoryctes, g. n. 



Genotype. N. tetradactylus {Oryzoryctes tetradactylus, 

 M.-Edw. & Grand.). 



No other species known, as (7. niger } Maj., appears to me 

 to be merely a melanism of N. tetradactylus. 



Very like Oryzorictes in most respects, but not quite so 

 highly modified for a fossorial life and with only four fore- 

 claws. Its fur is like that of other members of the group, 

 and not modified into the velvety condition of that of the 

 Talpidre, as is the case in Oryzorictes. The skull also is less 

 markedly ridged and broadened behind than in that genus, 

 nor is it so expanded at the tip of the muzzle. 



No special differential characters in the teeth. 



It may be here recorded that both Microgale cowani and 

 Nesoryctes tetradactylus possess a baculum in the penis. 

 The presence of this bone has been recorded in the larger 

 Tenrecidse, but no other Insectivores possess it. 



The bone in Nesoryctes is a simple slightly curved spicule 

 6 mm. in length, thickened at the proximal end. 



5. Oryzorictes, M.-Edw. 



Oryzoryctes, Trouess. (emend.). 



Genotype and only species. 0. hova, M.-Edw. 



XXXV. — The Baculum or Os Penis of some Genera of 

 Mustelidie. By R. I. POCOCK, F.R.S. 



Mr. Oldfield Thomas's paper upon the 0.9 penis— or the 

 baculum, as he appropriately names it — of the Sciuridse shows 

 that this bone, at least in the case of those rodents, has a quite 

 unexpected value, greater than that supplied by the skulls 

 and teeth, in determining the affinities of the genera. Very 

 possibly it has a similar systematic importance in other 

 groups of Mammalia, and deserves, in consequence, more 

 attention than has hitherto been given to it by osteologists. 



As has long been known, this bone is especially well 

 developed in the Arctoid and Cynoid Carnivora. It lias been 



