230 
W. M. Wheeler 
of Antedon rosacea^ at Naples are fonnd to be infested with a 
variable number — sometimes several dozen — specimens of this 
species. At tbis season tbe specimens vary from 0.2 — 2.5 mm in- 
length. v. Graff ('77) gives the size of this species as 4 mm, and 
I infer from this datum that all the specimens I have seen were 
young or little more than half grown. There may be but one brood 
dnring the year, but if this is the case, the period of oviposition 
must extend over several weeks or perhaps months. 
The ovaries — the » problematical Organs« of Nansen — are 
easily seen in horizontal sections through the mid-region of the body 
of specimens 1.75 — 2.5 mm in leugth (PI. 10 Fig. 1 ov.a and ov.p], 
They project as two deeply stainiug protuberances from either side of 
the intestine. The relations of these bodies to the body-cavity and 
gut-diverticula are more clearly apprehended in cross-sections (Fig. 4 
ov). Under a low magnification the cells of the ovary appear to be 
arranged in rows so that the organ often resembles a tuft or tassel. , 
As seen in the figure it lies just dorsal to the base of the intestinal 
ramification [mt.r). The continuity of the lumen of the intestine (int) 
and that of the ramification could be readily seen in the preceding 
section which I have not figured. The cavity into which the ovary 
projeCts is one of the body-cavity ramifications which in their total- 
ity have been wrongly called the ovary by all preceding writers , 
who have had occasion to mention these structures. The mere pre- 
sence of ova in different stages of growth in an organ does not of 
necessity make it an ovary, and this, I maintain, is the only evi- j 
dence which has been advanced in favor of such an interpretation. * 
It is quite evident that this criterion would make an ovary of the | 
body-cavity of any typical Annelid. I 
In Fig. 4 several ova in different stages of maturation are seen j 
along the dorsal boundary of the coelomic cavity and there are also j 
a few mature ova floating in the lumen of the ramifications. The j 
testes (^s) are well-developed and consist of masses of cells in all ; 
stages of spermatogenesis imbedded in the parenchyma of the dorsal 
part of the body. Similar masses occur also in the ventral paren- 
chyma and lateral to the parapodia in other sections. The vesiculäe 
seminales [v.s] are full of mature spermatozoa, still enclosed in plas- ^ 
matic masses and awaiting liberation into the water through the so | 
i V. Graff ('87, pag .4) found specimens of M. cirriferum also on another 
Crinoid, Antedon petasus, Düb. and Kor. 
