VERMES 



139 



tures attached to them are very rudimentary. The branchiae 

 practically disappear except on the segments immediately suc- 

 ceeding the head, and there they 

 are often very long and, like the 

 elongated tentacles on the head, 

 are very beautifully colored so that 

 as one sees them in an aquarium 

 they resemble the most delicately 

 colored flowers, the ugly body of 

 the worm being encased in its tube, 

 which suggests the stem of the 

 plant. The Errantia are carnivo- 

 rous worms, provided with a pro- 

 trusible pharynx and teeth ; these 

 are wanting in the Sedentaria, 

 which are herbivorous. 



SUBCLASS II. OLIGOCILETA 



The Ohgochaeta(Gr. 0X/70?, few, Fip I3I- Ser/>///(P with the i r tubes 



and Yam;, bristle) are much less ( After Quatrefages, from Parker and 

 , . , , .11 1 r. 1 Haswell's Manual.) 



highly organized than the Poly- 



chaeta. They live almost exclusively in fresh water, mud, and 

 in damp earth. They have no sharply differentiated head such 

 as is found in most Polychaeta, and consequently palps and ten- 

 tacles are absent ; with few exceptions there are no eyes. 

 Parapodia and branchiae are likewise wanting, but bristles, ox- 

 setae, are present though much less numerous than in the marine 

 worms ; they are generally arranged in rows along the sides of 

 the body, and are short, projecting only slightly beyond the 

 surface. 



In their internal structure the Oligochneta differ most strik- 

 ingly from the Polychaeta in the reproductive organs. The 

 number of these is greatly reduced, and both testes and ovaries 

 occur in the same individual, usually only one or two pairs of 

 each. Put although hermaphroditic, cross fertilization between 

 two individuals takes place, and the eggs are often inclosed in 

 a cocoon formed by a secretion of certain gland cells in the skin 

 of the worm. Each cocoon incloses a number of eggs, and there 



