SEX AND REPRODUCTION 65 



scribed as something like concentrated essence of fish, is the 

 product of a pair of glands situated beneath the skin near the 

 inguinal region, and opening on each side behind the bridge 

 connecting the upper with the lower shell. Freshly caught 

 specimens of this species, according to Dr. H. Gadow, stink 

 horribly when handled ; but after they have been kept in con- 

 finement for some time, they lose the habit of voiding the 

 contents of the glands every time they are taken up, and thus 

 become less objectionable pets. 



The North American " stinkpot-terrapin " {Cinosternum 

 odoratum) owes its ill-favoured name to the fetid secretion 

 exuded by the inguinal glands, which can scarcely be regarded 

 as intended otherwise than as a means of defence. 



Under the same category must doubtless come the habit 

 displayed by certain lizards (such as the scheltopusik) and 

 snakes (among them the common ring-snake) of ejecting when 

 handled the ill-smelling contents of the cloaca. 



The milky fluid exuded by the American milk-snake and 

 the blood squirted from the eyes of the so-called horned toad, 

 to which fuller reference is made in the concluding chapter of 

 this section of the present work, likewise come under the 

 category of fluids discharged for defensive purposes, whether 

 used in combat with rival males for the possession of some 

 coveted female, or to repel the attacks of enemies of another 

 kind. 



Many lizards inflate the body, the region of the mouth, or 

 special laryngeal sacs, for the apparent purpose either of 

 frightening enemies or as a means of sexual attraction, or 

 perhaps for both together. Examples of this are displayed by 

 the inflation of the body in Lacerta and PJirynosoma, in the 

 expansion of the frills of Chlamydosaurus, and the dilatation of 

 the gular sacs of Metopoceros and other iguanas. Such effects 

 might be enhanced, it is reasonable to suppose, by a swelling- 

 out of the head and protrusion of the eyes. Such a function, 

 according to Dr. H. L. Bruner in the American Journal of 

 Anatomy, vol. vii., pp. 1-117, is, however, insufficient to 

 explain the existence in the heads of both sexes of many 

 lizards and snakes of an apparatus of muscles and vascular 

 sinuses for producing excessive blood -pressure, and consequent 

 swelling in this region. In lizards, at any rate, this mechanism 



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