4O Invertebrate Zoology. 



appear as a greatly tabulated organ, extending nearly from 

 end to end of the animal, its lateral subdivisions giving 

 a segmented appearance. It is built on the Tricladid 

 type, one main branch or ramus extending anteriorly, and 

 two extending posteriorly. Both anterior and posterior 

 rami give off lateral lobes, the diverticula above mentioned, 

 the rounded ends of which frequently becoming further 

 subdivided. 



The Nervous System. The pigmented eyes are sur- 

 rounded in the living animal by a halo-like area, which 

 marks the location of the brain. This organ consists of a 

 pair of lobes, united across the median line by a commissure. 

 From the brain certain sensory netves extend anteriorly, as 

 transparent lines, while extending posteriorly, as transparent 

 bands, are the longitudinal nerve trunks, one on either side. 

 Note that each longitudinal nerve trunk, after extending 

 almost the full length of the animal, is united to its fellow 

 of the opposite side by a broad posterior commissure. Other 

 commissures will be found in certain favorable specimens 

 to pass transversely across the animal, and to extend later- 

 ally beyond the longitudinal trunks, nearly to the margins. 

 These are the transverse commissures, and their number 

 is about the same as the number of pairs of intestinal 

 diverticula. 



The Reproductive System. The Turbellaria are 

 mostly hemaphrodite. In the present species the ovaries 

 are to be found in adult animals as a pair of rounded organs, 

 located in the anterior portion of the body between the 

 second and third or third and fourth intestinal diverticula. 

 They are often more readily found if the mirror of the 

 microscope is shielded by the hand, thus viewing the 



