614 INSECTIVORA 



behind the axilla, and their exudation is probably protective, since 

 few carnivorous animals will eat the dead bodies of these creatures. 

 In both species of Gymnwa and in Potamogale large pouches are 

 situated on either side of the rectum and discharge their secretions 

 by ducts, opening in the first-named genus in front of, and in the 

 latter within the margin of the anus. In Centetes the ducts of 

 similarly situated racemose glands open by pores at the bottom of 

 deep pits placed at either side of the anus. 



The integument is thin, but in many species is lined by a 

 muscular coat, which is probably more developed in the Hedge- 

 hogs (Erinaceiclce) than in any other mammal. In this family 

 and the Centetidce most of the species are protected by spines 

 implanted in the panniculus carnosus muscle, and more or less 

 replacing the fur of the upper surface of the body. 



The order is usually divided into two suborders, but the very 

 aberrant genus which constitutes the first might well be raised to 

 ordinal rank. It has little in common with the true Insectivora, 

 but as it certainly belongs to no other of the recognised mammalian 

 orders it is retained among them chiefly to avoid the inconvenience 

 of increasing the number of ordinal divisions for the sake of a 

 single isolated form. 



Suborder Dermoptera. 



Upper and lower incisors compressed, multicuspidate, the lower 

 deeply pectinated ; fore and hind limbs connected by a broad 

 integumentary expansion forming a parachute. 



Family Galeopithecid-E. 



In addition to the characters given under the head of the sub- 

 order it may be mentioned that the orbit is nearly surrounded by 

 bone, the zygomatic arches are well developed, the tympanic forms 

 a bulla, the ulna is distally united with the radius, the tibia and 

 fibula are distinct, the pubic symphysis is long, the penis is pendent, 

 the testes are received into inguinal pouches, the mamma? are 

 axillary, the uterus is two-horned, and there is a large crecum. 



Galeojnthecus l — Dentition : i f , c \, p f , m f ; total 3-4. Second 

 upper incisor and canine with two roots. Two species — G. volans 

 and G. phUippinensis. The former, which is distinguished from the 

 latter by the form of the upper incisors, has a total length of nearly 

 2 feet. The long and slender limbs are connected by a broad 

 integumentary expansion extending outwards from the sides of the 

 neck and body, and forming also a web between the fingers and 

 toes as far as the base of the claws (Fig. 282) ; the hind limbs are 



1 Pallas, Acta Acad. Set. Imp. PctrojmJis, vol. iv. pt 1, p. 208 (1780). 



