44 THE ROTIFEBA. 



% 



at the tips. They are habitually thrown up under the helly. The eye is minute, pale- 

 red, occipital. The trophi are normal, long, and capable of being brought to the very 

 front, where they work vigorously. The whole head is protrusile, and very mobile. 



The entire animal is transparent and nearly colourless ; but the numerous folds and 

 corrugations impart an appearance of a blue-black tinge to the body. The form and 

 outline are subject to slight but continual changes, contracting and expanding. The 

 animal is lithe and active, but not locomotive. A single specimen has occurred in water 

 from Sutton Park ditch, Birmingham, in the orange-coloured sediment which abounds 

 with fine Desmidieae. 



Length (of lorica), ^ inch ; (total) T ^j inch. Habitat. Sutton Park. P.H.G.] 



D. MINNESOTENSIS ; D. OHiOENSis, Herrick (175). Insufficiently described. The latter 

 is said to have a quadrate plate projecting over the base of the foot. 



MONOSTTLA MOLLIS, Gosse (170), (PI. XXXI. fig. 41). 



[SP. CH. Body oblong, sub-cylindric, clothed with a soft, flexible, corrugated skin, 

 instead of a lorica ; toe rod-shaped, short, thick ; claw obscurely two-shouldered. 



I venture to claim specific rank for this form, which has the same relation to Mono- 

 styla as D.flexilis has to Distyla and Cathypna. That both are immature conditions 

 would be a natural conclusion, but that, so far as my experience goes, all Loricate Rotifera 

 are hatched with the lorica already developed. And that such is the case with Monostyla 

 in particular, the following note will show. The facts, apart from their relation to this 

 question, may be of interest. 



In August 1885, an egg of M. cornuta, in my live-box, displayed the young moving 

 vigorously within the hyaline egg-shell, slowly revolving. The lorica was already well- 

 defined, evidently without folds, though expansile in retraction, distinctly broad oval in 

 outline, smooth and rotund when viewed lengthwise. The imprisoned animal grew 

 much larger, so that it almost filled the long diameter of the shell, but not nearly its 

 short diameter. Its length was now 7 ^ inch. 



After I had watched for about an hour, during which its restless motions had nearly 

 ceased, the frontal cilia were seen vibrating at the very edge, and in a moment more 

 outside the edge, of the shell. For an instant it recoiled ; but returned again and 

 again to the effort, at each time protruding more and more. At length it pushed fully 

 half out, then hung a moment, as if exhausted. Now another vigorous lashing of the 

 cilia, and out it is bodily, yet still adhering to the shell by the glutinous toe-point, 

 whereby it now drags the shell hither and thither. At last it is quite free, evidently 

 ovate, stiff and smooth, as the normal adult. 



These facts, which were recorded during the actual process, seem sufficient to show 

 that, in this Family at least, the chitinous consolidation of the lorica is attained before 

 birth. And the corollary follows, that, in D. flexilis and 3/. mollis we have examples 

 of illoricate condition in a loricate family, analogous to Alastigocerca stylata in the 

 Rattulida. 



I have examined many specimens from various waters. In one case the animal 

 contracted to a cordiform outline, as if possessing a lorica, which yet was very mem- 

 branous. "When eagerly chewing, not only the mallei worked, but a pair of additional 

 horn-like pieces, well in front of the mastax. A very small and indistinct red eye is 

 near the occipital extremity of the brain. 



Length, ^ to ^ inch. Habitat. Lacustrine. P.H.G.] 



MONOSTYLA CLOSTEKOCERCA, Scliuuirda (135), (PL XXXIV. fig. 7). 



SP. CH. Lorica depressed, obtusely toothed in front ; eye very small and round; 

 jaws triangular ; foot spindle-shaped. 



The lorica is oval with its anterior portion excised so as to give it a shallow circular 



