there is a circular chitinous plate, the proximal being continued 

 in the vas deferens, the distal (fig. 8) exhibiting a somewhat 

 depressed area, in the centre of which a fine opening occurs, 

 limited by a network of delicate chitinous stripes, which form 

 together a regular rosette. This rosette — termed the coronula 

 — is again surrounded by a thickened chitinous ring, giving 

 off radiating stripes to the periphery. — Regarding the nature 

 of this peculiar organ, it has long been misunderstood by the 

 naturalists, the erroneous view maintained by Zencker as to 

 its being a glandular auxiliary organ — „ mucous gland" — 

 having generally been accepted. Prof. Weissman has however 

 suggested a very different explanation of the organ in question, 

 and his view has also been fully adopted by Mr. Nordqvist. Ac- 

 cording to these distinguished naturalists, the organ has the 

 signification of an ejaculatory apparatus, by the action of which 

 the spermatozoa are forced through the vas deferens during 

 copulation, and this view I have also myself found wholly confir- 

 med by direct observations on living specimens. If my opi- 

 nion is correct, that the spermatozoa after having left the testicular 

 tubes are not contained within any distinct canals, but simply 

 accumulated in the body-cavity, the organs, besides, would seem 

 to act upon the body-cavity as a sort of pumping-work, whereby 

 the spermatozoa lying nearest to the upper end of the apparatus, 

 are, as it were, one by one sucked up into the organ through 

 the so-called coronula, and by the same action expelled through 

 the other end within the vas deferens. This peculiar movement 

 of the organs I have in fact once directly observed on examin- 

 ing under the microscope a very pellucid male specimen of 

 Candona fabteformis Fischer. 



The spermatozoa of the Cyprididse are highly remarkable by 

 their comparatively colossal size, as also by their apparently very 

 complicate structure. They have been minutely examined by Zen- 

 cker, both in their perfect state and in their several developing faces. 

 I have myself studied closer the spermatozoa of the present species 

 and give below some few notes on their structure. Each fully develo- 

 ped spermatozoon has the form of a very elongated and fine thread- 



