EXTERNAL CHARACTERS. 69 



ii. The apertures of the oviducts are similarly 

 situated in the fourteenth segment. They are 

 small pores not seen so easily as the male 

 apertures, their lips not being tumid. 



iii. The apertures of the spermothecse or receptacula 

 seminis, of which there are two pairs, are 

 situated in the grooves between the segments 

 and in the line of the outer row of setae, the 

 first pair between segments ix. and x., the 

 posterior pair between segments x. and XI. 



d. The excretory apertures are best seen in a specimen 

 which has been hardened in spirit, and dried with 

 a cloth immediately before examination. Each 

 segment, except the first three and the last, has 

 one on each side, either on the ventral surface a 

 little in front of the outer seta of the inner double 

 row, or, in some segments, high up on the side 

 of the animal. 



To see these apertures, strip off the cuticle from the anterior 

 part of the worm, and examine the worm with a pocket lens, 

 squeezing it slightly so as to cause fluid to exude from the 



e. The dorsal pores, though small, are often visible to 

 the naked eye. They open mid-dorsally in the 

 grooves between the segments, and place the 

 ccelom in communication with the exterior. 



The first one is between segments x. and xi. 

 and opens into segment xr. Behind this point 

 they occur regularly in every intersegmental 

 groove. 



Make a drawing to show the external characters. This is 

 best done by dividing two facing pages of a large note-book 

 transversely into three spaces by two lines half the width of a 

 page apart. Continue the lines right across from one page to 

 the other, thus giving the centre lines for the drawings. Now 

 rule about 35 lines, a quarter of an inch apart, across the centre 



