BDELLOURA OR SYNCGELIDIUM. 49 



Draw the male reproductive system. Refer to charts and 

 text-books for anything that is obscure. 



The female organs are as follows: 



(a) Opening into the genital atrium are the two large sacs, 

 the so-called uteri, which lie near the margins, just posterior to 

 the end of the pharynx. Each has a separate opening on the 

 ventral surface of the body, but has no direct connection with 

 any other part of the reproductive system. These may not 

 be homologous with the single uterus found in most triclads. 

 (See Wheeler.) 



(6) Place a worm ventral side up and look carefuly be- 

 tween the second and third or the third and fourth anterior gut 

 diverticula on either side of the main anterior ramus for the 

 two ovaries. 



(c) The oviducts pass backward from the ovaries, parallel 

 to the vasa deferent ia, and unite posterior to the penis. The 

 common duct thus formed enters the posterior part of the geni- 

 tal atrium. The oviduct is difficult to demonstrate and it may 

 be necessary to try both fresh and stained material. 



(d) Along the margins of the animal, between the divertic- 

 ula of the gut, are rounded bodies, the vitellaria. These dis- 

 charge their products into the oviducts. Do you know what 

 they are for? 



Draw the female reproductive system. 



Study stained and mounted specimens for any points 

 which have not been found, and particularly examine the ner- 

 vous system. Look for the marginal nerve running along the 

 edge of the body, and for numerous transverse commissural 

 nerves. How many of these are there? How regular is their 

 arrangement? 1 



Wheeler: Synccelidium pellucidum, a new Marine Triclad. Jour. Morph., 

 9, 1894. * 



1 A Polyclad, Planocera, can be obtained without difficulty from the 

 mantle chamber of Busycon. If Busycon is allowed to remain out of 

 water for some hours the Planocera usually crawl out. The form is fairly 

 satisfactory for study. 

 4 



