308 



ANIMAL BIOLOGY. 



[Part II. 



palps, or labial tentacles (/. p.) are seen as triangular backward- 

 directed processes, on either side, just beneath the mouth. They 

 are highly vascular and richly supplied with nerves. Dorsal to 

 the gills is seen a large transparent sac filled with fluid, the 



'' T>.ad. 



FIG. 90. MUSSEL GENERAL ANATOMY; DIGESTIVE ORGANS. 



a. ad. Anterior adductor muscle, a. r. m. Anterior retractor muscle, au. 

 Auricle, d. gl. Digestive gland, d. d. gl. Duct of digestive gland, ex. si. 

 Exhalent siphon. /. Foot. g. gl. Generative gland, i. g. Inner gill. in. si. 

 Inhalent siphon. Tc. o. Organ of Keber. I. p. Labial palp. m. Mouth, o. g. 

 Outer gill. p. Pore. p. ad. Posterior adductor muscle, p. c. Fericardial 

 chamber, p. p. Protractor pedis muscle, p. r. m. Posterior retractor muscle. 

 pal. Mantle, pr. Probe passed from exhalent siphon between the inner gill 

 and the foot. r. Rectum, re. Renal organ (organ of Bojanus). s^. Stomach. 

 ty. Typhlosole. v. Vent. ve. Ventricle. 



pericardium (p. c.), within which the heart may be dimly seen. 

 Beneath the pericardium is seen through the body-wall the 

 greenish brown tissue of the organ of Bojanus or renal organ (re.}. 



