Mycetomorpha. 585 



of tlie mantle (PI. 16 Fig. 5). One of these bodies is represented 

 at a higher magnification in PI. 16 Fig. 8. There is a large central 

 mass of small cells, with small darkly staining nnclei and thin 

 cuticle, strongly similar to the embryonic cells of the Cypris larva. 

 Surronnding this mass is an Investment of a yellowish substance, 

 coniposed of globules, which does not take np borax carmine, and 

 is, in fact, yolk. There is an onter cuticnlar envelope and in the 

 peripheral yolk there are situated two or three large cells, very 

 vacuolated, with a darkly staining nucleus. Very often too, large 

 vacuoles appear in the yolk, as in the cytoplasm of the oocytes. 



When the eggs occur in the ovary they are regularly rounded. 

 and the central mass of cells is spherical, but when on the other 

 band they are found in the mantle-wall they are flattened and 

 distorted in shape and the central cells may tend to disperse. 



Among the Cypris larvae in the brood pouch there is a small 

 Proportion of bodies of a similar size and appearance, bnt of a 

 regulär ovate shape. These I believe to be eggs which have 

 not developed further into Cypris larvae but for some reason or 

 other have degenerated. In most cases the structure is still re- 

 cognisable and similar to that of the eggs in the ovary and mantle 

 in that there is a central mass of small cells surrounded by a 

 layer of yolk globules, but the cells are more distributed and stain 

 less definitely than in the other cases (PL 16 Fig. 9). But so evident 

 is the connection between the two kinds of bodies that I cannot 

 resist the conclusion that the "developing eggs" in the mantle, do 

 normally dehisce into the mantle cavity, 



I have carefully examin ed the complete series of sections 

 but without finding a trace of a testis or any System of genital 

 •ducts. While any conclusions as to the methods of reproduction 

 in this animal must be provisional at present, I suggest that 

 Mycetomorpha is parthenogenetic, that the embryos undergo the first 

 part of their development in the body, larval life being abbreviated 

 by the Omission of the Nauplius stage, and that tlie embryos find 

 their way into the brood pouch without the agency of special ducts. 

 Finally, if my Suggestion as to the nature of the problematical 

 bodies in the ovary and mantle is correct, we may suppose that, 

 when the developing embrj^os attain a certain size, they migrate 

 from the ovary into the mantle, passing between the inner ecto- 

 •dermal lining and the muscular layer. They then break through 



Zool. Jahrb. XXXIII. Abt. f. Syst. 39 



