424 DR. A. FARRE ON THE STRUCTURE OF THE CILIOBRACHIATE POLYPI. 
Parietal granules and muscles distinct. The gizzard wanting in 
this and all the following species. 
Fig. 6. Empty cell showing the operculum terminating in setae. 
Plate XXIV. p. 403. 
Lagenella repens. 
Fig. 1 . Natural size, parasitic on Sertularia. 
Fig. 2. X 40. Portion of the same. The animals in various positions and stages of 
growth, connected by a creeping stem, and mixed with Membrani- 
pora pilosa. 
a. Side of the cell indented by the pressure of the surrounding fluid 
when the animal protruded. 
Fig. 3. x 100. a. Animal protruded. 1. Triangular space in the pharynx. 2. Stomach 
during digestion. The hepatic follicles large and very distinct. The 
food tinged with their secretion. The pylorus well marked. 3. Pa- 
rietes separated from the sides of the cell by the action of the pa- 
rietal muscle. 4. Notched margin of operculum. 
b. and c. Two animals retracted. The operculum drawn towards one side by 
the single retractor. The stomach suspended by the intestine from 
the top of the cell ; at b 2. the stomach is seen pale and empty, 
and the hepatic follicles barely visible, b 3. Parietal muscles. 
This figure ( b .) exhibits the appearance invariably presented by all 
the animals of this class when they have remained for a day or two 
without emerging from their cells, and consequently without a fresh 
supply of food ; emptiness of the stomach, being in every case 
accompanied by a pale and nearly transparent state of its parietes, 
and a reduction of the follicles to the finest points ; while the full 
stomachs appear as represented at a. These characters are so 
striking when pervading an entire specimen, as at a glance to fur- 
nish the observer with a ready test of the purity of the water em- 
ployed, and of the degree of vigour of the little animals under 
examination. 
d. Figure showing the muscles. 1. Gastric. 2. Tentacular and 4. Oper- 
cular retractor. 3. Two sets of parietal muscles. 
e. e. e. Geinmse in various stages. 
Fig. 4. Parietal muscles in a state of relaxation. 
Fig. 5. The same in a state of contraction. Their diameter doubled. 
