of the Bay of Naples. 95 



an undulately denticulate inner wall, a peculiarity which is 

 probably to be ascribed to the muscles there situated. Soon 

 after its entrance into the neck the oesophagus receives on 

 each side the efferent duct of an elongate-pyriform unicellular 

 gland (fig. 6, dr^), which extends into the head and evidently 

 represents the ^' 5-6 flask-shaped cells " which are said to 

 occupy the same position in Seison. To the third segment of 

 the neck belong two (or more?) small glands (fig. 2, dr^), 

 which likewise discharge into the oesophagus and by their 

 secretion facilitate the downward passage of the food. 



The stomach (figs.l, 2, l^,st) forms an elongated sac, ctecally 

 closed behind, which is formed of large polygonal cells. The 

 latter are arranged in irregular longitudinal series, and, iu a 

 well-nourished individual, densely packed with brown pig- 

 ment-particles. If the animals be allowed to starve for a 

 time, these disappear, and in an individual just escaped from 

 the egg they are not yet developed. It is remarkable that 

 the cells bear no cilia on the inner surface, a condition which, 

 so far as I know, has not hitherto been observed in any other 

 Rotatorian. It is, indeed, often difficult to detect the delicate 

 cilia in the stomach of the Rotatoria ; but I have definitely con- 

 vinced myself of their absence in many very favourable animals. 

 Indirectly the correctness of this statement is confirmed by 

 another observation. Thus, in the lumen of the stomach there 

 are frequently a great number of oil-globules of different 

 sizes, and these, when the stomach is perfectly quiescent, 

 remain quite motionless, even when they lie close to the wall, 

 which would be impossible if motile cilia were present. Clans 

 also noticed no vibratile movement in Seison. At the anterior 

 end of the stomach, above the point of entrance of the 

 oesophagus, two glands come in, which do not deviate from 

 the ordinary structure of these organs. In the hinder wall 

 the cellular coat of the stomach is somewhat thicker than 

 elsewhere, but it does not allow the smallest trace of even a 

 rudimentary intestine to be recognized. By the absence of 

 this, Paraseison may easily be distinguished from Seison, as 

 the latter, according to the last published observations of the 

 Viennese naturalist, possesses, in both sexes, a rectum 

 opening with the sexual apparatus. The food of Paraseison 

 appears to me to consist chiefly of vegetable detritus and of 

 particles of the eggs of iVe5a?«'a which have become decomposed ; 

 at least I often saw the stomach densely filled with a mass 

 permeated by numerous fat-drops, which I regard as yolk. 

 Probably the loss of the cilia of the stomach is to be ascribed 

 to a readily absorbable form of food of this kind, standing in 



