CHAP, xvi THE HEDGEHOG FAMILY 509 



There is, furthermore, a distinct tendency towards a dis- 

 appearance of functional milk teeth, which is best seen in 

 Sdrex, where there are only seven milk teeth, none of which ever 

 cut the gum. This suppression of the milk dentition is like that 

 of the Marsupials, Edentates, and Whales, all of which appear to 

 be the first certainly are ancient forms of mammalian life. 



There is also a fairly well-defined, though shallow, cloaca in 

 many genera. Finally, the testes are purely abdominal in some, 

 and in none is there a full descent into a scrotum, as in the more 

 highly-developed Eutheria. 



SUB-ORDER 1. INSECTIVOKA VEEA. 



Fam. 1. Erinaceidae. This family contains the genera 

 Erinaceus, Hylomys, and Gymnura. 



Hylomys, considered by Dobson to fall within Gymnura, is 

 kept separate by Leche. 1 H. suillus is a Malayan animal, small in 

 size, about 5 inches long, with a short tail. Like Gymnura it is 

 spineless. The ears are decidedly large and nude. There is one 

 pair of inguinal and one pair of thoracic teats. The colour 

 above is a rusty brown with yellowish-white under parts. The 

 palms and soles are quite naked. In its general form it recalls 

 Tupaia very much more than its own immediate relatives. 

 There is no doubt, however, of its systematic position when the 

 skeleton and teeth are examined. A variety has been described 

 from altitudes of 3000 to 8000 feet on Mount Kina Balu in Borneo. 

 It has the complete dentition of forty-four teeth. There are 

 fourteen pairs of ribs. As in Gymnura the tibia and fibula are 

 united below. The genus is considered by Leche to be the oldest 

 existing type of Erinaceidae. 



Gymnura^ is also a Malayan form with the complete dentition 

 of the last, but with fifteen pairs of ribs and a longer tail, con- 

 sisting of twenty-three vertebrae as against fourteen. There is, 

 as with Hylomys, but one species, G. rafflesii. This animal has 

 a peculiar odour, resembling decomposed cooked vegetables. 



1 "Bemerkungen iiber die Genealogie der Erinaceen." In Festschrift f. 

 Liljeborg, 1896. See also Anderson, Trans. Zool. Soc. viii. 1874, p. 453. 



2 Dobson, "Notes on the Anatomy of the Erinaceidae," Proc. Zool. Soc. 1881, 

 p. 389. 



