492 



CHORD AT A, 



Order I. — Mofiotremata, 



There are two families in this order — (i) Ornithorhyn- 

 chidae and (2) Echidnidae, closely allied in many ways. 

 Ornithorhynchus anatinus, or the duckmole, is found in the 



Australian region. Its 



Fig- 337-— Fore (A) and Hind (B) general appearance may 



Foot of the Duckmole. be seen from the figure. 



The body, usually about 

 18 inches long, is cover- 

 ed with dense, soft, 

 brownish hair, and the 

 head has a remarkable 

 pair of horny " beaks." 

 The eyes are small and, 

 as in most aquatic forms, 

 there is no external ear. 

 Both pairs of limbs have 

 five digits wdth claws and 

 a " web " or membrane 

 is present in the front 

 limb, none in the hind. 

 The tail is flat, and in 

 old specimens the hair 

 is absent from its lower 

 surface. In habits the 

 duckmole is " fossorial " 

 and '^aquatic." It swims 

 freely and lives in deep 

 burrows in river-banks. 

 At the end of its burrow 

 it constructs a nest in 

 which it lays its eggs. 

 There are no teats and 

 the mammary glands 

 are modified sudorific 

 glands. The teeth are 

 only present in the young and adolescent forms and 

 appear to be worn away early, when they are replaced 

 by the familiar horny pads or " cornules " found in most 

 skulls. The teeth are only molars and few in number, eight 



Note the webbed fore-foot and the poison-spur 

 (rt) on the hind-foot. 



