178 CHOEDATA. 



stigmata, lined with actively moving cilia. Of what use are these 

 cilia? 



2. On each side of the pharynx six longitudinal pharyngecJ 

 folds will be seen. - 



3. The endostyle is a ciliated groove along the mid-ventral 

 wall. Anteriorly it is continuous with the peri-pharyngeal cili- 

 ated bands, which encircle the oral end of the pharynx. From 

 the point where they unite dorsally the dorsal lamina extends 

 backward along the mid-dorsal line of the pharynx. At its 

 posterior end will be seen the small opening into the esophagus. 



Do you understand how the animal captures its food and 

 how the endostyle, peri-pharyngeal bands, and dorsal lamina are 

 used? 



4. In front of the anterior end of the dorsal lamina note the 

 small, volute-shaped dorsal tubercle. This is the extremity of 

 the hypophysis, a tube connecting the subneural gland with the 

 oral cavity. 



5. A ring of oral tentacles will be seen in the mouth, anterior 

 to the peri-pharyngeal bands. Of what use are tentacles in 

 the mouth? How many tentacles are there? 



6. The very short esophagus opens into the stomach, which 

 will be recognized by the brown digestive glands that cover 

 it. From the stomach the intestine forms a loop on the left 

 side, and is easily traced to the anus, which opens dorsal to the 

 pharynx in the atrial chamber. A longitudinal fold, the typh- 

 losole, extends throughout the intestine. What is the use of 

 such a fold? 



Reproductive System. On each side of the body, adherent to 

 the inside of the mantle, is an elongate hermaphrodite gland. 

 Each gland consists of a lighter part, the testis, and a darker part, 

 the ovary. The gonoducts open on the outer wall of the atrial 

 cavity near the base of the atrial siphon. Each consists of two 

 ducts, oviduct and vas deferens. Microscopic examination of 

 the oviduct may show the presence of eggs. 



Excretory System. The renal organ is a conspicuous, elon- 

 gated sac on the right side. It contains a brownish fluid and 

 usually some solid matter. It does not possess a duct. 



