of Edinburgh , Session 1880-81. 
63 
Styela. 
Dorsal lamina in the 
form of languets. 
S. bythia. 
Dorsal lamina ribbed 
transversely and 
slightly pectinated. 
S. flava. 
Dorsal lamina plain , 
margin even. 
Tentacles few, about 12. 
Tentacles at least 30. 
Long and short 
alternately, 
S. squamosa. 
All one length. 
Shape oblong ; Shape hemispheri- 
length = twice the cal ; length = 
breadth. breadth. 
S. oblonga. 
S gTans. 
Tentacles 30, 
all one 
length. 
Tentacles 
more than 
30, large and 
small. 
Only one in- 
ternal longi- 
tudinal bar 
between each 
pair of folds. 
S. exigua. 
Several inter- 
nal longitudi- 
nal bars be- 
tween each 
pair of folds. 
Mantle thick, free 
from test. 
S. gyrosa. 
Mantle thin, united 
to test. 
20 large ten- 
tacles, and 
smaller in- 
termediate 
ones. 
30 large ten- 
tacles, and 
smaller in- 
termediate 
ones 
Body stalked ; horns 
of olfactory tubercle 
turned in. 
Body sessile ; horns 
of olfactory tubercle 
not turned in. 
S. grandis 
S. lactea. 
S. clava. 
S. convexa. 
Styela bythia , n. sp. 
External appearance. — Shape between cubical and hemis- 
pherical ; anterior end broad and obtuse, dorsal and ventral edges 
sloping backwards and slightly outwards. Attached by a wide 
posterior end slightly expanded at the margin. Apertures sessile, 
inconspicuous, four cleft ; branchial at the ventral and atrial at the 
dorsal end of the anterior extremity. Surface of the test flat hut 
rough, especially at the anterior end. Colour dark-brown, paler at 
the posterior end. Length, 2 cm. ; breadth, 1 cm. 
Test thick, very stiff, but rather brittle ; white on section and 
on the inner surface. 
