ON THE GENUS NOTOPYGOS, 245 
Notopygos sibogae, n. sp. 
Siboga-exped. Stat. 144, Anchorage north of Salomakiee 
Island; Stat. 169, Anchorage of Atjatuning; Stat. 234, 
Nusa-Laut-Island. 
Length of the largest specimen 35 mm, its breadth 
8'/, mm. (without bristles); the number of its segments 
amounts to 30. 
Body of an elongated oval shape, somewhat obtuse ante- 
riorly, tapering posteriorly; its lateral sides rectangular. 
On the dorsum of each segment there is an area having 
the shape of a triangle, the base of which is formed by the 
frontal margin of the segment, whereas the top lies on 
its middle; from the middle of the base of the triangle a 
line is running to its lateral sides, dividing thus the trian- 
gular field into three smaller ones. The dorsal side colour- 
less, except a narrow, violet band around the notopodium 
and a violet stripe over the middle of the accessory cirrus 
of the anterior five segments; ventral side buff coloured, 
whereas the palps have a dusky hue like the horizontal 
plate of the caruncle. The caruncle extends to the 6th 
segment; its horizontal plate is furnished on each side with 
16 to 17 folds. The unpaired antenna short, measuring about 
one third of the length of the caruncle. The mouth seems 
to be limited by the 4th segment, that is folded longitu- 
dinally. The branchiae commence on the 5th segment; the 
anus is situated on segment 23 at the top of a papilla. 
The dorsal setae are greenish, the ventral ones opalescent. 
All the bristles bifurcate, smooth, except those of the first 
segment that have the long limb more divergent, with 
four faint serrulations. 
The smallest of the specimens described in this perio- 
dical, Vol. VIII, 1886, p. 168, that from Amboina, probably 
belongs also to this species and was incorrectly identified with 
Notopygos crinitus ; for in this species the anal opening is situ- 
ated on the posterior part of segment 21, according to Ehlers, 
on the intersegmental groove 21/22, according to Grube. 
Notes from the Leyden Museum, Vol. XX XIII. 
