Earthworms of the Vienna Museum. 125 
rior end of the atrium in the eighteenth segment ; it is rather 
long and coiled, and opens on to the exterior without any 
terminal dilatation, ‘The structure of the atria is thus very 
interesting, inasmuch as they present us with characters 
intermediate between the “ lobate”’ and “ tubular ” form of 
atrium. As both forms of atria are met with in the Periche- 
tide, though the lobate is the more common type, the inter- 
mediate condition is required. 
Close to the point where the atrium perforates the body- 
wall on its way to the exterior is a sac containing penial 
sctea. These sete differ (see fig. 13) from those of Mega- 
scolex armatus, the only other species of the eee in which 
they have been hitherto figured. ‘They are sharply bent at 
the extremity, which is beset fora short distance with minute 
denticulations. 
Corresponding to the papillae which I have referre] to in 
describing the external characters are four round white glands. 
“Pericheta brachycycla,’ Schm. 
This is also a Megascolex ; there is nothing but the colour 
to distinguish it from Megascolex cingulatus, since the clitellum 
was undeveloped, and since I have not been able to compare 
the internal organs. As there is the colour difference I shall 
for the present assume the distinctness of the species, and 
rename it 
(5) Megascolex brachycyclus (Schm.). 
Re a brachycycla, Schmarda, Neue wirbell. Thiere, Bd. i. Hiilfte ii. 
we: 
Lee ee brachycyclus, Vaillant, Annelés, p. 88. 
The characters upon which Schmarda relied to distinguish 
the species from the others described by him was the form of 
the sete ; it is now known that the form of the setx cannot 
be relied upon for the discrimination of the species of Per?- 
cheta. This is certainly my own experience, and Prof. 
Bourne, who has examined a large number of species, remarks 
that, except in special cases, the shape of the seta “ is of little 
use for classificatory purposes.” 
The dorsal and ventral gaps in the circles of sete are not 
perhaps so well marked as in MZ. cingulatus. 
The first dorsal pore is, as in that species, between seg- 
ments v./vi. 
The oviducal pores are double. 
The male pores are upon the eighteenth segment; in front 
fo) 
of and behind each of them is a genital papilla; these lie, as 
