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hump dorsally, a well developed ihree joint foot; cuticula very hyaline. Wheel-or^an 

 a ciliary wreath encircling a disc in the middle with a broad elevation, carrying 

 along its borders a series of long hairs. Of the alimentary canal a large ligament 

 which embraces the testis and reaches the corona; it seems to contain a number 

 of small oilglobules. There is a large brain with a red eye and two nerves which 

 run up to the dorsal antenna, situated upon the top of the hump. Two lateral 

 antennæ. The excretory organ consists in two curled lateral canals with three or 

 four vibratile tags, but I have not been able to lind any contractile vesicle. Testis 

 very large, containing two sorts of spermatozoa; it is suspended by means of a 

 ligamentum or inducium; on the dorsal side, the ligamentum is fastened at 

 four or five points on the transversal bands. Two prostata glands. Genital opening 

 dorsally on the first foot joints; ductus seminalis coated with cilia and a hunch of 

 cilia round the opening. A large oilglobule over the testis. At all events three pairs 

 of longitudinal muscles for the wheel-organ and six or seven very conspicuous 

 transversal muscle bands. In the foot two foot glands. Size: male 160 //, female 450 /(. 

 Notops brachionus which seems to be a rare animal eyerywhere, is never found 

 in this country. I have vainly been in search of it for many years. The males which 

 have been used for the above given description have kindly been forwarded to me 

 by Dr. Rousselet in 1907. He sent me some females which arrived safe and laid 

 male eggs; a few males were hatched. Later on Mr. F. E. Cocks has been kind 

 enough to forward to me two slides of males and a drawing. By means of this 

 foreign material the above given drawings have been worked up.' 



General remarks. 

 It is characteristic of the males of this interesting family that they are only 

 slightly reduced; the size is only about half that of the female; more in Rhinops, 

 not quite so much in N. brachionus. The form is the same as that of the female; 

 this especially holds good for Rhinops and Hijdatina. The wheel-organ resembles 

 that of the female sex and in Rhinops is almost identic in the two sexes. Rhinops 

 is one of the few known Rotifers with full development of the alimentary canal, 

 with mouth, mastax, gasti-al glands and intestine (anus?). In the two other species 

 only the common rudiment exists; a brain with dorsal and lateral organs is most 

 probably always present; the eye is wanting in Hijclalina senta; traces of retro- 

 cerebral organ most probably present; further investigations necessary. Two lateral 

 canals with three or four pairs of vibratile tags; no contractile vesicle; a large 

 testis, prostata glands, no real penis; the ductus seminalis turned inside out, when 

 used as such. Sacs with opaque contents often or always over the testis. Highly 

 developed muscle system, which needs further investigation. 



Brachionidæ, 



The family contains the three genera: Noteiis, Brachionus and Schizocerca; only 

 the males of the genus Brachionus are hitherto known. 



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