22 



]U(Miil)iaue. Tt is possible, however, that the\- luav he due 

 to shrinkage in the j)iocess of })ieservatiou. ^\s has 

 alieady been seen, the only space of this kind which occurs 

 in Linens f/esserensis is a small one between the proboscis 

 sheath and the oesophagus. The space between the intes- 

 tine and the inner longitudinal muscle la^'er is small, and 

 is occupied by connective tissue cells and their inter- 

 cellular substance. 



In this s[)ace occur sacs alternating with the 

 intestinal diveiticula (IM. III., figs. (I and 8), and 

 with the intestinal diverticula (PI. III., tigs, (i and 8), and 

 lined ])y connective tissue cells. These are the gonads 

 whose cavity, ap})arent iu the young animal, becouics 

 obliterated in the matui-e worm by the sexual cells which 

 fill it, and whitdi aie probably derived from the connective 

 tissue cells which form its lining. Each gonad jiossesses 

 a duct which opens dorso-laterally (PL III., fig. 8, fj(f.), 

 and which is foimed partly bv a prolongation of the con- 

 nective tissue lining of tln^ gonad, and partly from an 

 ectodermal depression . 



The sexes are separate, and in the breeding season, 

 which lasts fiom about Febiuary till -lune, the 

 female dejiosits her ova under stones in a long 

 tubular gelatinous cord. In the walls of this coid are the 

 ova contained in small Hask-shaped transparent capsules 

 (PI. III., tig. 7). One of the gelatinous cords produced 

 by a single female usually contains a hundred or more of 

 these little capsules, and each capsule contains the con- 

 tents of a gonad, i.e., from one to seven ova, according to 

 the size of the female. The spermatozoa of Linens 

 (/cssei-eiisis possess a long pointed head (PL IV., fig. 4). 

 The o-elatinous cord containing the ova is said to be the 

 joint production of the male and the female. Into it the 

 male then proceeds to discharge spermatozoa. Soon 



