292 



ANIMAL BIOLOGY. 



[Part II. 



Both cuticle and calcareous layers are secreted by the posterior 

 edge of the collar. 



There are six external apertures. Beneath (1), the mouth, is 

 (2), the opening of the pedal gland (p. g.). Below the posterior 



st. 



d. d. cjl 



FIG. 85. SNAIL : DIGESTIVE ORGANS, HEART, AND PULMONARY VESSELS. 



A. External characters of snail. B. Snail dissected to show digestive 

 system, pulmonary chamber, heart, and renal organ. 



a. t. Anterior tentacle, an. Anus. ait. Auricle, col. Collar, cr. Crop. 

 d. d. gl. Duct of the digestive'gland. d. gl. Digestive gland, d. s. gl. Duct 

 of salivary gland, g. a. Genital aperture. Ti. j. Horny jaw. int. Intestine. 

 m. Mouth, m. 6. Muscular band. o. s. d. Opening of salivary duct, oil 

 Odontophore. p. a. Pulmonary aperture, p. gl. Pedal gland, p. t. Posterior 

 tentacle, p. v. Pulmonary vessel. . r. Rectum. T. s. Radula sac. ren. 

 Renal organ, s. gl. Salivary gland, st. Stomach, v. Ventricle. 



tentacle on the right side is (3) the genital aperture (g. a.). In 

 the collar there is (4) a large pulmonary aperture (p. a.) leading 

 into the lung ; and close to this, on its right side, a larger aper- 

 ture (5), the vent, and closely associated with this (6), a smaller 

 orifice, by which the duct of the renal organ terminates. 



