INTRODUCTION. xxvii 



one which comes behind it in the permanent dentition. The first pre- 

 molar above and below, and the true molars, have no milk-predecessors. 



In most species the upper sectorial is much longer than the first 

 upper molar, but in this respect there are many degrees of difference ; 

 nor are the relative sizes of the various teeth always quite constant even 

 in the same species. 



Myology. The muscles* of the Dog are formed and arranged, for 

 the most part, as in the Carnivora generally. Comparing them with 

 those of the Feline Carnivora, it may be mentioned that there is but a 

 single dorso-epitrochlear and no supinator longus. The latter fact is in 

 harmony with the habitual action of the Dog's fore limb, which is almost 

 exclusively used for running and walking, and not for climbing or 

 movements which require the paw to be bent sole upwards. The ex- 

 tensor communis digitorum gives off only four tendons. The plantaris 

 is large, and its tendon gives origin to \hsflexor brevis. The tendons 

 of the flexor longus digitorum pedis and of the longm hallucis unite 

 together as in the Cats, and, as in them, an elastic ligament connects 

 the last phalanx of each digit with the penultimate phalanx, so that 

 when the foot is dissected the claws are seen to be slightly retracted 

 in fact, although their retraction is not visible externally. 



The rectus muscle takes origin from the triangular fibrous or fibro- 

 cartilaginous structure before described! as attached to the brirn of the 

 pubic part of the pelvis. The tendons of bolh the external and 

 internal oblique muscles forming the inner pillar of the abdominal 

 ring are inserted into the inner side of the same fibrous structure, 

 while the outer pillar of the abdominal ring is formed by part of the 

 external oblique inserted into the outer margin of the same, the 

 pectineus being attached to its ventral surface. 



Splanclmokgy\. The mucous membrane of the edges of the lips, 

 especially of the lower lip, is developed into a number of delicate 

 sensitive processes. The lower lip is firmly bound down to the gum in 



* For information concerning muscles, see ' The Cat,' chapter v. 

 t See above, p. xxi. 



t See ' The Cat,' chapters vi. to ix. The viscera have been described by Professor 

 Flower, C.B., in the ' Medical Times ' for 1862, p. 621. 



