SEA-FISHERIES LABORATORY. 225 



pair of feet is represented by minute papilla?. The caudal 

 stylets are very short, and furnished with three or four 

 short plumose setae at the apex. 



The external openings are the mouth, the vulvae, the 

 openings of the vasa deferentia and the anus. 



The mouth is situated on the ventral surface of the 

 cephalo-thorax, at the apex of a conical tube, composed 

 of the upper and lower lips fused together. In the very 

 early cyclops stage the lips are not fused. The vulvae and 

 openings of the vasa deferentia are placed at the posterior 

 angles of the genital segment. The anus is at the apex of 

 the abdomen, in the middle line. The vulvae open into 

 the receptacula seminis, which are in direct communi- 

 cation with the oviducts. 



The whole of the genital segment and abdomen in the 



female is marked by fine transverse lines. The colour, 



which is arranged in patches, varies from dark violet to 



light red. 



Alimentary Canal. 



In the adult the mouth opens into the intestine, which 

 probably acts as the stomach, the . oesophagus and true 

 stomach having disappeared in the metamorphosis of the 

 cephalo-thorax. The intestine is at first narrow where 

 it passes through the neck, then it widens considerably in 

 the swollen part of the genital segment, contracting 

 slightly in the abdomen, and finally terminates in a short, 

 narrow rectum leading to the anus (Plate V., fig. 4). 

 The intestine is lined with a single layer of nucleated 

 cells. Attached to this layer, and in some cases embedded 

 in it at irregular intervals, are large cells filled with fine 

 granular material. In some parts these large cells are 

 grouped together two and three rows high. In other 

 parts they are quite free (Plate V., figs. 5 and 6). The 

 layer supporting the nucleated cells appears to be com- 

 p 



