] 38 



AKIRA IZTJKA. 



anterior region and deeper in the posterior — say, in the posterior $ of the 

 body-length. This deeper tone of the colour is evidently due to the eggs 

 contained in the region. The males are of a very light pink color, which 

 may bear a milky-whitish tint on attaining sexual maturity. Both 

 sexes show a slight iridescence all over the body. 



In fresh specimens the segments are externally indistinct or scarcely 

 recognizable in the anterior region, though they are always plainly 

 indicated in the posterior half of the body. After preservation they are 

 marked by distinct ring-grooves all throughout the entire body. 



The mouth, situated on the ventral side of the anterior end, is 

 subtriangular in shape. The cephalic lobe in front of it bears, as usual, a 

 pair of horn-like tentacles which are widest at base and are directed 

 antero-laterally. They are only about 1 mm. long. Eyes are wanting. 

 There exists, on each side of the head and at about the level of the 

 mouth, an oval-shaped vibratile pit, the greater axis of which is vertically 

 disposed. 



The body gradually narrows behind in the part adjoining the 

 anal segment. This segment is broadest at base, where it is broader 

 than the part directly in front of it. It again narrows towards the 

 terminally situated anus. The anal margin is nearly entire or is at most 

 wavy, forming obsolete lobes eight in number. In its anterior half the 

 anal segment bears numerous papilla? arranged in a number of longitudinal 

 rows or zones, — which arrangement, as also the peculiarities of the anal 

 orifice, forms one of the characteristic points by which the species may 

 be distinguished from all the others. Three filiform appendages occur 

 on the anal segment : one on the dorsal side in the median line and the 

 rest ventro-laterally on either side. 



Observed on sections, a thick cuticle is found to cover the hypodermis, 

 beneath which I have failed to discover ring-muscle fibres. Neither do 

 these seem to exist inside the layer of the strongly developed longitudinal 

 muscles, this layer being directly lined by the peritoneum on the inner side. 

 A dorsal and a ventral mesentery suspend the intestine in the body-cavity. 

 Neither longitudinal nor ring muscles are present in the intsstinal wall. 



