146 THE AMERICAN MONTHLY [July, 



Two eyes may sometimes be seen in Rotifer tardus^ in the neck, 

 just above the mastax, which possibly might cause confusion ; these be- 

 long to a foetal animal ; but one has to look so far down before one 

 comes to the second mastax that it might be a means of easily separat- 

 ing closely allied species. The head is upwards in Rotifer vulgaris 

 and tardus^ downwards in Philodina aculeata, Philodina tuber culata^ 

 and Rotifer macrurus^ but is this invariable? 



The color of this rotifer varies considerably, probably chameleon- 

 like from the tint of the flocculent deposit in which it lives ; some may 

 be found quite a light yellowish-brown ; these are the younger ones ; 

 in these the internal organs are more easily seen ; the mastax is sur- 

 rounded by a considerable glandular mass, the buccal funnel stands out 

 like a pouch from the front of the animal, its margin fringed with cilia, 

 and leads straight down to the mastax, immediately under which is a 

 lai^ge oblong stomach separated by a constriction from a similar shaped 

 but smaller intestine ; on the other side an oval ovary fills up the body. 



The antenna (Fig. 3) is long, two-jointed, the joint very faintly 

 marked ; at the end are three small lobes fringed with cilia. The 

 frontal column (Fig. 3) is rather wide in proportion to its length ; 

 among the cilia a small cleft proboscis may be seen immediately before 

 the wheels expand. The tubercules are not well marked, and appear 

 to be formed by the folds of the trunk ; in its fully extended state, when 

 it becomes worm-like, resembling Rotifer vulgaris^ the tubercules 

 almost disappear. 



Philodina actileata, frequently found with the one under consider- 

 ation, is of a yellow hue, has the distinctive spines, the wheels do not 

 exceed the width of the body, the spurs are small, and the end joint of 

 the antenna is wedge-shaped, base foi'ward. 



DISTYLA FLEXILIS. 



This rotifer, belonging to the family Cathypnada;^ which includes the 

 cominon Cathypna luiia^ is represented in front view, Fig. 4, and in 

 side view, Fig. 5. Mr. Gosse places it in the genus Distyla with some 

 hesitation ; there is indeed but little distinction between Distyla and 

 Cathypna^ the former being longer in proportion to width, and the 

 curious lateral, bellows-like, infolding characteristic of the family being 

 less marked. 



In this group may be observed something like a state of sleep ; the 

 animal perches on its claw-like toes, bent at an angle under its body, 

 and remains motionless for a time, as if visited by that " gentle sleep 

 beloved from pole to pole," which most rotifers seem not to require. The 

 little rotifer has to exercise greater perseverance than the little ant to ac- 

 quire its daily provender, and, examine it when you may, from morn 

 to dewy eve, or in the silent watches of the night, it is ever in a state 

 of ceaseless activity. This group is intei"esting from being an excep- 

 tion to this general rule. 



Distyla fexilis is small, about yi^-inch long and without color, ex- 

 cept the one rose-red oblong eye, and a yellowish tinge in the stomach. 

 The body is covered with folds, giving it an irregular tesselated ap- 

 pearance and making the outline fuzzy under a low power. It is active 

 in its attacks on food, but remains near one spot for a long time, occa- 

 sionally swimming about to seek " fresh fields and pastures new," yet 



