— A) — 
internal structure as in Temmnocephala; but the same holds good of Sphyranura and 
perhaps also of some other Monogenaea. 
Very elose is the resemblance between Zemnocephala and the Rhabdocoela in 
the system of accessory glands secreting rounded granules eonneeted with the male 
reproductive apparatus. Von Graff’s account of these structures as they occur in the 
Rhabdocoeles applies equally well, word for word, to Temmocephala — the only diffe- 
rence of consequence being in the much greater length of the duets in the latter 
case. The so-called *“prostate-glands” of some Monogenaea are evidently: the same 
structures less specially developed. 
Stalked eggs similar to those of Zemnocephala oceur among the Rhabdocoeles 
— the “stalk” in some of the latter, as in some of the species of the former, not 
always serving for attachment. But similar eggs are met with also among the 
Monogenaea. 
Suffieient data are wanting for a eomparison of the embryological history in 
the various groups under discussion. What is known does not seem to tell more in 
one direetion than in another. The embryo of Temnocephala undergoes direet deve- 
lopment, and beeomes fully formed while still within the egg — the reproductive 
apparatus alone remaining undeveloped. "This direct development and absence of 
metamorphosis it shares equally with the monogenetic Trematodes and with the Rhab- 
docoeles. 
On the whole, on reviewing the evidence, I am inelined to think that the 
Trematode affınities of Temnocephala preponderate over the 'Turbellarian. It presents 
an assemblage of characters which distinguish it very broadly from any individual 
member of the former class; but perhaps it has rather more important points of 
resemblance in the various features of its structure with, now one, now another family 
of Trematodes than with the Rhabdocoeles. 'T’'he large ventral sucker, the exeretory 
saes, and the nervous system may be set down as deeidedly Trematode and not 
Rhabdoeoele in character. "The preponderanee, however, if it occurs, is only slight, 
and I should see little reason for finding fault with anyone who regarded 7emmo- 
cephala as an aberrant Rhabdocoele specially modified in accordance with a peculiar 
mode of life. 
