KEFERSTEIN, ON SAGITTA. 135 
the ovary in every respect just as Wilms has already described 
it. Along its outer side is the thickened ovarian wall, and 
within this is excavated the oviduct, which probably possesses 
an internal orifice in front, and, posteriorly, opens externally 
in the well-known papilla. 
Krohn has likewise observed this canal in all sexually 
mature individuals; he regards it, however, not as an ovi- 
duct, but as a seminal receptacle. I found this canal almost 
always filled with the long, thread-shaped zoosperms, which 
projected in a tuft from the papillary orifice of the ovary, 
and thus, like a probe, indicated the opening of the lateral 
canal in this papilla. At its anterior end I could, indeed, 
directly make out no entrance of the canal into the ovary, 
and am, therefore, unable to determine whether it be an ovi- 
duct or seminal receptacle, though the former seems to me 
the more probable, especially because I almost constantly 
found within the ovary several very large eggs, which ap- 
peared to be undergoing development. One must infer from 
this an internal fecundation of the ova; but the observed 
condition of the eggs agreed so little with the history of their 
development given by Gegenbaur, that I dare not venture 
any positive opinion. 
Setigerous tufts—As Wilms and Krohn have already 
pointed out, little bundles of fine, stiff, often very long hairs, 
occur on the surface of Sagitta, when uninjured. Usually 
these sete are pretty regularly disposed behind one another 
in a dorsal and ventral series, and the fins are placed 
between these series along the body, so that at first sight one 
is reminded of the setigerous tufts of the Annelids. But 
the sete of Sagitta, as Krohn has already stated, and as I 
have particularly observed in S. serrato-dentata, Ky., of Mes- 
sina, rests on the epidermis, composed of rounded clear cells, 
‘037 mm. in length, with granular contents, which is raised 
up into an eminence beneath each setigerous tuft. The setz 
are merely outgrowths of the membrane of one of these epi- 
dermic cells. 
If one of the above epidermic eminences be examined with 
a high magnifying power, it seems to be traversed from its 
base to the setigerous cells by a fibrous tract, which can be 
traced backwards to the so-called ventral saddle, in which 
these fibrous tracts terminate in a radiate manner. Krohn, 
as is well known, has declared this (often very large) ventral 
saddle to be a nervous ganglion; in regard to which point I 
myself, with W. Busch, cannot doubt that this excellent 
investigator has fallen into error, for the ventral saddle lies 
outside the muscular coat of the animal, and stands in no 
