On the Generic Division of the Hedgehogs. 193 



12. Marmosa elegans Cinderella, Thos. 



<J. 11,25, 19, 51 j ?. 50. Leon, Jujuy. 



Type-locality. Tucuroan. 



Mr. Budin notes that this little opossum is the culprit 

 when rats and mice captured iii the traps are found partly 

 eaten. But it is certainly not always so, as I found in 

 La Plata that the common Akodon arenicola freely eat their 

 comrades in like case. 



XX. — The Generic Division of the Hedgehogs. 

 By Oldfield Thomas. 



(Published by permission of the Trustees of the British Museum.) 



In t he most recent paper on hedgehogs, that by Satunin*, 

 these animals are divided into three genera — Erinaceus, Hemi- 

 nhinus, and Macroechinus, — the divisions being based on 

 certain characters of the pterygoids and bulla} first pointed 

 out and used by Dr. John Anderson. 



But Satunin'a paper, based as it is on Asiatic material 

 only, and drawn up without access to the full literature of the 

 subject, proves to need some modifications and corrections as 

 to nomenclature, and the following notes may be of use to 

 persons wishing to understand the grouping of these animals. 



As material increases and has to be classified, labelled, and 

 arranged in Museum collections, this close splitting of the 

 genera proves to be of great assistance in carrying out the 

 work with accuracy and convenience, and on this account I 

 folh w Satunin in using the groups as full genera. 



(Synopsis of genera : — 



A. Pterygoids and bullae normal t- 



a. Spines on crown divided into two groups by a 

 median parting. Postglenoid pr> cesses small, 

 not hollowed out, much surpassed by the mas- 

 toid procef 

 « 2 . Hallux present. 



a 3 . Coronal parting narrow, inconspicuous. 



* Ann. Mus. St. Petersb. xi. p. 1 (1007). 



+ As in Anderson, P. Z S. 1805, p. 41tj, fig. 1, and J. A. S. B. xhii. 

 pi. iv 



