258 CLASS xv. 



than the rest, and is not perforated but grooved l . In these last the 

 excretory duct of a gland is received in the groove, the gland 

 agreeing in texture with the superior maxillary salivary gland 

 or seeming merely to be a lobe of it, whence it has been supposed 

 that these serpents do not belong to the venomous division. 



The large perforated tooth, placed on each side of the mid-plane 

 at the fore part of the mouth, is the means by which the venomous 

 serpents inflict wounds and shed the poison into them. The poison 

 is secreted by a gland of an elongate form which is situated behind 

 and under the eye upon the upper jaw, and is compressed by the 

 temporal muscle. It consists of blind tubes, which in some are un- 

 divided, in others ramified and disposed in flat lobes or plates that 

 are separated from each other by partitions of the membrane that 

 surrounds the gland 2 . The long excretory duct of this gland runs 

 forward and ends in a membranous sheath which surrounds the 

 base of the poison- gland; here the poison is received in an aperture 

 situated in front of the base of the tooth. Besides this gland there are 

 still others in the head of serpents, viz. along the edge of the upper 

 and lower jaw, under the tongue, and lastly a lachrymal gland behind 

 the eye; these glands are common to the venomous and innocuous 

 serpents, yet all of them are not always equally present. The poi- 

 son-gland, on the contrary, is peculiar to the venomous serpents, 

 and in these the other glands of the head, especially those along 

 the margin of the jaws, are generally less developed 3 . 



As to the poison itself, it is an unctuous gelatinous fluid, without 

 taste, and drying in the air into little plates or scales ; it long retains 

 its injurious power, is soluble in water, insoluble in spirit of wine 

 and volatile oils, and is generally stated to be neither of an alkaline 

 nor an acid nature 4 . CANTOR, however, has found that the poison 



1 H. SCHLEGEL, Onderzoeking van de speekselklieren der slangen met gegroefde tan- 

 den, in vergelijking met die der niet giftige en giftige, in the Bijdragen tot de natuurk. 

 Wetenschappen, n. 1827, bl. 536 551, and in the Nov. Act. Acad. Cces. Leop. Tom. 

 XIV. DUVERNOY afterwards treated this subject more at large, Annales des Sc. not. 

 Tom. xxvi. Paris, 1832, pp. 113 160, PI. 5 10, and again in a Supplement, ibid. 

 Tom. xxx. pp. 632. 



3 See J. MUELLER, De glandularum secernentium structura penitiori, pp. 55 57. 

 PI. vi. fig. 13. 



3 Compare on these different glands, besides DUVERNOY loc. cit., also MECKEL in 

 his Archivf. Anat. u. Physiol. 1826, s. i 13, Tab. I. figs, i 10. 



4 See the celebrated work of F. FONTANA, Traite sur le venin de la vipere, &c. 

 Florence, 1781, n. Tom. 4to. 



