4 Dr. Augusta Ärnbåck-Christie-Linde. 
. ÆTT 
is covered with small retracted Bryozoa) whence the surface 
looks as if it were dotted with tiny whitish tubereles (cf. 
Pl. 1, fig. 1). Some shells of Foraminifera are also attached 
to it. The surface is free from other foreign matter. — 
The left side by which the animal is attached is whitish 
and opaque. 
The specimen measures 34 mm. in length and 19 mm. in 
breadth. The expanded base measures 28 mm. in breadth. 
Internal structure. 
The upper i. e. the right side of the test is thick and 
of leathery consistency. The inner surface is smooth and. > 
provided with a nacreous lining. The left side of the test 
— by which the specimen is attached — is thin. 
The mantle musculature is powerfully developed on 
the right side and round the siphons as regards. both the 
horizontal and the longitudinal layer. On the left side it is. 
thinner and not so well developed. 
The tentacles are short and conical and of different 
size. Their exact number could not be ascertained. 
Atrial tentacles are present in great number. They 
are slender and club-shaped, scattered over a broad velum. 
The dorsal lamina is plain-edged and rather broad: 
Transversally it is strongly folded, probably owing to contrac- 
tion of the tissues. Its posterior part is apparently double. 
(ef, FLA, sfie. 2), | 
As appears from the last-mentioned figure, the dorsal 
tubercle is of a very characteristic structure, differing, so 
far as I know, from that of all other known Styelae. lt is 
prominent and of rounded form with two small openings of 
semi-circular shape, the concavity of which is directed to the left. 
The ganglion situated behind the dorsal tubercle is 
rather long. 
The branchial sac resembles that of a typical Styelid. 
In the specimen at my disposal it is highly contracted. It is 
provided with four well-marked longitudinal folds on each 
side, each fold with numerous vessels, at least 12—15 in number. 
The stigmata are elongated and of the usual form. On the inter- 
spaces between the folds about 8—10 longitudinal vessels are 
