416 C. F. ROUSSELET ON PROALES WERNECKI. 



numbers of eggs, I noticed swimming in the water a few small 

 and very slim rotifers, which I isolated and found to be males 

 (Figs. 2 and 3), with a large sperm sac and usual copulatory 

 organ, and also possessed of fully formed jaws ; the stomach, with 

 small gastric glands attached, is also present, but takes up a very 

 small portion of the body cavity ; the intestine could not be seen ; 

 the oesophagus is very long, and is moved about with a snake-like 

 motion. The salivary glands attached to the mastax are very 

 large and conspicuous in the young female ; in the male they are 

 also present, though smaller. The toes and foot-glands are large 

 and strong in the male, but a contractile vesicle could not be 

 found. 



The jaws, which are the most peculiar feature of this male, are 

 like those of the female in shape, and represented in Fig. 4. All 

 the usual parts are well developed, and, in addition, there is a 

 small triangular plate on each* side articulated between the ramus 

 and uncus. I have made the drawing of these jaws very carefully 

 from a good view obtained by dissolving them out with caustic 

 potash. It will be noticed that Dr. Rothert's figure of the rami 

 differs somewhat from the same parts in my drawing. The exact 

 delineation of these very minute jaws is very dime u It, however, 

 and a correct interpretation is almost impossible without dissolving 

 out with potash. 



The young female (Fig. 1), when first hatched, is much of the 

 same size and appearance as the male ; but the large white 

 rounded salivary glands attached by a narrow neck to the mastax, 

 and the large and full gastric glands, as well as the ovary and 

 stomach, which together fill up the whole body cavity, serve to 

 distinguish it at once. 



Both the young male and female escape from the galls in which 

 they have been hatched by an opening which is formed at the 

 apex. They swim about in the open water for a time, and the 

 young female then again enters a Vaucheria filament, but where 

 and by what means is not exactly known yet. Having entered 

 the filament, it causes the plant to produce a rounded or elongated 

 gall of considerable size, where the rotifer can move about, and 

 spends the rest of its life eating the green cell contents of the 

 walls of the gall, and laying eggs to the number of forty to sixty. 

 The female, it appears, is unable to develop and lay eggs outside 

 the Vaucheria filament or gall. The adult female is extremely 



