190 



ZOOLOGY. 



to enter the mouth of their parent, who swallows them and 

 keeps them in her stomach until the danger is past. 



Most snakes resemble in color the ground or soil they fre- 

 quent; some being, as in the rattlesnake of the western 

 plains, of the color of the soil in which they barrow; the 

 little green snake is of the color of the grass through which 

 it glides; others are dull gray or dusky, harmonizing with 

 the color of the trunks of trees on which they rest. The 

 poisonous coral-snake {Elaps) of the Central American for- 

 ests is, however, gayly and conspicuously colored; indeed, it 



Ftg. 233. — Head of the rattlesnake, a a, poison gland and its excretory duct; c, 

 anterior temporal muscle; /, posterior temporal muscle; g, digastricus; h, ex- 

 ternal pterygoid muscle; i, middle temporal muscle; q, articulo-maxillary 

 ligament which joins the aponeurotic capsule of the poison gland; r, the cer- 

 vical angular muscle; t. vertebro-mandibular muscle; u, costo-mandibular 

 muscle. After Duvernoy. 



can afford to be brightly colored, as no birds dare to at- 

 tack it. 



The Salenoglyph poisonous snakes may always be recog- 

 nized by their broad, flattened heads, and usually short, 

 thick bodies. The poison gland of the rattlesnake (Fig. 

 233, a) is a modified salivary gland. The two fangs are 

 modifications of maxillary teeth, each of which has been, 

 so to speak, pressed flat, with the edges bent towards each 

 other, and soldered together, so as to form a hollow cylin- 

 der open at both ends, the poison duct leading into the 

 basal opening. When the fangs strike into the flesh, the. 



