266 Bulletin American Museum of Nedural History. [\o\. XX^^^, 



Eriiiaceus and Centetes. In the Soricoidea also the cartilaginous snout in 

 the eml)ryo is prolonged far beyond the premaxillaries (c/. the cartilaginous 

 snout of the embryo Centetes, the prenasal ossicle of Solenodon and the bony 

 rostrum of Nccrolcstes). Finally the Soricoidea resemble the Erinaceidse 

 and the Centitid^ in the possession of a common type of malleus : one with 

 "a wide lamina and a processus gracilis [Folii] united to the tympanic ring 

 after the fashion of the Marsupials" (Doran, 1S79, p. 444). 



Winge has suggested {cf. van Kampen, 1905, p. 452) "dass die Uberein- 

 stimmung zwischen Talpicloe und Clirijsochloridce nicht bloss durch Anpas- 

 sung zu erkliiren ist. . . .sondern Avohl -wirklich auf Verwandtschaft beruht" 

 (van Kampen). But the numerous resemblances cited above, as well as 

 certain generalized Centetoid features of Necrolesfes, seem only to warrant 

 the inference that the stem form of the Soricoidea (which was doubtless not 

 yet jNIole-like in its limbs) is related to the stem of the Centetoidea on the 

 one hand and to the stem of the f^rinaceoidea on the other. 



Erinaceoidea. The Erinaceida', through the more primitive genera 

 Gymnura, lli/hmii/s and the Oligocene Protcrix, seem to be linked securely 

 to the very primitive Eocene and Oligocene Le[)tictidi:Te. Of these the less 

 specialized forms of the genus Ictops are more primitive than the typical 

 Erinaceidse in many characters especially the following: the skull as a whole 

 is mesaticephalic whereas in Erinaceus it is brachycephalic with the muzzle 

 broad and short ; the zygomatic arches are well developed, the post-glenoid 

 and post-tympanic processes are separate, the palate is not fenestrated, the 

 pterygoidal ridges are single (/. e., there are no ectopterygoid fossfe), the 

 tym])aiiic wings of the basisphenoid if present are but moderately developed; 

 and the "tympanic" or postglenoid ridge of the alisphenoid is well developed 

 {cf. Microgale). 



I'he dentition also is very primitive: the canines remain subcaniniform, 

 p| are retained, the upper molars (in Ictop.s-) are of a simple tritubercular 

 type with a low hypocone and narrow anteroposteriorly ; the milk dentition 

 persists until the animal has attained adult stature. 



llie common origin of the Erinaceoidea and the Centetoidea is indicated 

 especially by the following characters: In both families the malleus is of the 

 same type, namely with the processus gracilis very .broad and perforated by 

 the chorda tympani nerve (Doran, 1S79, p. 444), while the incus and stapes 

 in the two families are also closely similar (Doran, /. r., p. 440, pi. 62, figs. 

 11-14). The base of the cranium in Centetes and Erinaceus presents very 

 numerous resemblances recorded above (pp. 244, 245), especially the median 

 ])it, the median foramen for the chorda, the strong development of the 

 tympanic wing of the basisphenoid, the course of the three branches of the 

 entocarotid artery and the arrangement of most of the foramina. Ivcche lays 



