2U 56 



found in the pelagic region of smaller lakes; besides, it is a pronounced pondform 

 occurring together with B. pciki. With regard to sexual periods, maxima, number of 

 eggs etc. it is in accordance with B. pala; still the cluster of male eggs is not so 

 large, the number not being above from six to eight. 



Schizocerca diversicornis Daday. 



Tub. XII, fig. 3—4. 



Male: Description: Body somewhat flattened, ahnost rectangular. A well de- 

 fined lorica, consisting of a dorsal and a ventral plate, the first provided with some 

 peculiar elegantly curved lines (see figure).. Lorica rather thick: no spines. A forepart 

 which can be wholly withdrawn into the lorica; a relatively well-developed foot 

 with two joints and two short toes. The wheel-organ consisting of a ciliary wreath, 

 surrounding a cone-shaped disc; the top of the cone carries a strong bunch of long 

 bristles; on the sides of the cone two strong, long setæ. Of the alimentary canal 

 remains only a band running forward from the testis below the brain. This is ex- 

 tremely large, carrying a red eye; there is a conspicuous dorsal antenna and two 

 lateral antennæ, lying near the posterior edges of the body. Owing to the thickness 

 of the lorica I have not been able to see the lateral canals; there is no contractile 

 vesicle. Testis very large; two large prostata glands. Penis of quite the same struc- 

 ture as described in B. pala, only when fully extended still larger and thicker. When 

 not used, fully retracted. 



A chitinous tube ending with a disc and glands round the tube: no special 

 penis muscles. Dorsally. behind the dorsal antenna and over the posterior part of 

 the testis two round globular masses, containing a number of opaque, sharply edged 

 grains. Only some longitudinal retractors of the wheel-organ seen. Size of male 160 /i, 

 of female 300 ,«. 



Schizocerca diversicornis is common in larger ponds and smaller lakes; it is here 

 a pronounced plancton organism; it is a stenotherm summer form, with maximum 

 at highest temperatures and sexual period in Aug. — September. The female carries 

 one or two parth. female eggs, rarely more than four male eggs and one resting egg. 



General remarks. 



In the structure of the males of the fam. Brachionidæ I especially wish to call 

 attention to the following facts. 



The males are very small, strongly reduced. There exists, at all events in the 

 two genera Brachionus and Schizocerca, a real lorica, consisting of a dorsal and a 

 ventral plate; spines are always absent, and so also is aU other equipment of the 

 lorica (facetted structure etc.), even if these structures are highly developed in the 

 female. The wheel-organ can be wholly retracted into the lorica, but commonly not 

 the foot; this is always present, provided with two toes. The number and place of 

 bunches of cilia and long stiff single setæ vary from species to species: a retroce- 

 rebral organ has never been observed ■s^^th certaintv. Rudiments of the alimentary 



