130 LIVERPOOL BIOLOGICAL SOCIETY. 
vessels are relatively large. The stigmata are few, and are 
arranged so as to form well developed spirals. There are 
a large number of very delicate membranous connections 
between the vessels. Some of these are very wide and 
break up the stigmata considerably (Pl. XIII., fig 9). 
The Endostyle is large and conspicuous. 
The Dorsal Lamina is a narrow plain membrane. 
The Tentacles are very large. There are about sixteen 
altogether: they are of two sizes placed larger and smaller 
alternately. The smaller ones are about one-third of the 
size of the larger (Pl. XIII., fig. 10). The latter are very 
much branched, and the numerous minute twigs are all 
slightly knobbed at their ends. 
The Dorsal Tubercle has a simple horse-shoe shape with 
the opening turned to the side. It lies in a deep peri- 
tubercular area (Pl. XIII., fig. 11). 
The specimens from Puffin Island contain embryos and 
tailed larve in their peribranchial cavities. The larve 
have a well developed tail, and a single pigmented sense- 
organ (Pl. XU, g.712). 
Molgula hancocki, n. sp. (Pl. XIILI., figs. 1 to 6). 
External Appearance: Shape ovate, elongated antero- 
posteriorly, scarcely compressed; posterior end tapering 
into a mass of matted hair-like filaments. Apertures at 
the anterior end, near one another, slightly prominent. 
Slightly covered with sand anteriorly, more closely en- 
encrusted in its posterior half (Pl. XIII., fig. 1). Colour 
lightish yellow. Length 1'5cm. Breadth lcm. Thickness 
8 mm. 
The Test is fairly thick in its posterior part, thinner 
anteriorly; it is smooth and glistening on its inner surface. 
The prolongations of the test to which sand grains are 
attached are long and closely placed at the posterior end, 
