E. MAESHALLI. — KEPKODUCTIVE ELEMENTS. 187 



Somewhat enigmatic is the process by which are formed the 

 bodies unhesitatingly called by me, because of their structure 

 (p. 162), the larvœ, in Leucopsacus orthodocus and Viirollula 

 fertile. As before mentioned, the larvœ in both these forms were 

 found in different stages of development. Deferring the details 

 of my observation on this matter to a further Contribution, it 

 is incumbent on me to mention here that, in a certain early 

 developmental stage, the embryo is spherical in shape and con- 

 sists of a compact mass of small cells, which mass is super- 

 ficially delimited by a layer of cells, whose general appearance 

 is like that of the internal cells, but which show an epithelium- 

 like arrangement. There is as yet no flagellation discernible on 

 the external surface, nor are the first spicules developed in the 

 internal cell-mass. The embryo occupies a position in the in- 

 current lacunœ between the chambers, being apparently devoid 

 of a special follicular envelope. As a still earlier stage, directly 

 preceding the one just mentioned, there is found a simple cellular 

 mass, agreeing in all respects with the latter excejDt in having 

 no distinct epithelial covering. And, that simple cellular mass 

 is in all appearance nothing else than an advanced stage of what 

 I have called the archseocyte-congeries, of which there exists a 

 series of different sizes, leading down uninterruptedly to the 

 little groups of cells so commonly found on the chambers. At 

 all events, there is nothing else than these compact groups of 

 small cells to which the origin of the developing embryo can be 

 traced back with any degree of probability. 



brood. That this belonged genetically to that very specimen and was not of extrinsic 

 origin, is fairly admissible on tlie ground of the very large number of young present. 

 The case may be construed as indicative of the fact that the formation of young broods takes 

 place in a short period of time and then in great profusion. The specimen referred to was 

 obtained during the month of May. 



