298 Mr. H. M. Kyle on the Nephridia, 



cellular tissue .... attached to the nephridium." This is 

 correct, but longitudinal sections through the nephridia with 

 the part of the body-wall to which they are attached show 

 more. These cellular masses are then obtained in position, 

 and their relation to the parts around made out. The drawing 

 of a transverse section by Benham gives a good idea of their 

 position and shows, moreover, that the cord of cellular tissue 

 of which Cunningham speaks runs down from the ventral lip 

 of the nephrostome and sustains the upper portion of the 

 gonad, while from the dorsal lip at its posterior end a blood- 

 vessel runs to the same place. But this is not the only 

 portion of the gonad. Springing from the epithelium lining 

 the body-wall other cellular masses may be seen, and it is to 

 these, 1 think, that Cunningham refers, being larger and 

 more obvious than the upper portion in direct connexion with 

 the neck of the nephridium. These masses lie immediately 

 below the posterior dilated portion of the nephridium, and 

 seem to have no connexion either with each other or with 

 the upper portion of the gonad. They seem to have arisen 

 by simple infoldings of epithelium into the body-cavity, and 

 present the appearance of a palmate leaf, the veins being 

 represented by a tissue composed of elongated cells, whilst 

 round the edges is the tissue giving rise to the ova or sperm- 

 mother-cells. At the base of the gonad is a blood-vessel ; 

 this is a prolongation of the branchial artery, and runs up 

 from these masses through the upper portion of the gonad to 

 the posterior extiemity of the vascular processes on the dorsal 

 lip of the nephrostome. Hence this blood-vessel connects the 

 different portions of the gonad with one another. 



Small worms answering to the descriptions given by 

 Benham (2) and by Ehlers (5) of the post-larval stages of 

 Arenicola are obtained here in the deep-sea tow-nets during 

 the spring. Although got later than those mentioned by 

 Benham, they are really younger, the largest specimen being 

 O millim. in length. They are most frequently obtained in 

 April and May, but in the middle of June 1895 a single 

 specimen, of length 3*5 millim., was procured. This shows 

 that the spawning-period must be spread over several 

 months. 



The gelatinous tube which envelops the animal is of a 

 strong yet flexible nature. The movements are executed by 

 means of wriggling the tail from side to side like an eel, and 

 the tube bends with every movement. The little worm is 

 thus able to swim easily through the water. 



The attempt to cut longitudinal sections of specimens 

 having the investing tube was a failure, owing to the firmness 



