EXPLANATION OF THE PLATES. 
PLATE I. Fig. 1. Hydra vulgaris, var. b, natural size : specimens from Yet- 
holm Loch, Roxburghshire. Fig. 2. H. vulgaris, var. a , nat. size and 
magnified. 
PLATE II. Fig. 1. Coryne squamata, nat. size and magnified. Fig. 2. C. 
squamata, loaded with reproductive gemmules. Fig. 3. The same magni- 
fied. Fig. 4. Variety of C. squamata, £jg. 5. The same magnified. 
PLATE III. Fig. 1 Tubularia indivisa, nat. size. Fig. 2. Head of the same 
magnified. Fig. 3. Tub. Larynx, nat. size. 
PLATE IV. Fig. 1. Hermia glandulosa, var. nat, size. Fig. 2. The same 
magnified. Fig. 3. Tubularia Larynx, var. nat. size. Fig. 4. The same 
magnified. Fig. 5. Gemmules, magnified. 
PLATE V. Fig. 1. Tubularia ramea, nat. size. Fig. 2. A portion of the same 
magnified. Fig. 3. Tubularia Larynx, var. nat. size. Fig. 4. A portion 
of the same magnified. 
PLATE VI. Fig. 1. Thoa halecina, nat. size. Fig. 2 A small variety of the 
same. Fig. 3. A piece of the stalk magnified. Fig. 4. A piece of the poly- 
pidom magnified. 
PLATE VII. Fig. 1, 2. Thoa Beanii, nat. size and magnified. Fig. 3, 4. Thoa 
muricata, from a specimen communicated by Mr Bean. 
PLATE VIII. Fig. 1. Sertularia polyzonias. Fig. 2. A variety of the same. 
Fig. 3. The same magnified. Fig 4, 5. Sertularia rugosa. Fig. 6. A creep- 
ing var. of Sert. rugosa, magnified. 
PLATE IX. Fig. 1. Sertularia rosacea, of the nat. size. Fig. 2. A portion 
magnified. Fig. 3, 4. Sertularia pumila. Fig, 5, 6. Sertularia pinnata. 
PLATE X. Fig. 1, 1.* Sertularia abietina, of the nat. size and magnified. 
Fig. 2. Sertularia tamarisca. Fig. 3. A portion magnified. Fig. 4. The 
ovarian vesicle, copied from Ellis. 
PLATE XI. Fig. 1, L* Sertularia filicula, nat. size and magnified. Fig. 2, 2.* 
Sert. operculata. Fig. 3, 3.* Sert. argentea, var. in a young state. 
PLATE XII. Fig. 1. Sertularia argentea. Fig. 2. The same in its young state. 
Fig. 3, 4. Portions of two different specimens of the same magnified, to 
shew the variations of the cells. 
PLATE XIII. Fig. 1, 2. Sertularia cupressina, from a specimen presented to 
me by J. V. Thompson, Esq. 
PLATE XIV. Fig. 1, 2. Thuiaria thuja, nat. size and magnified. 
PLATE XV. Fig. 1,2. Thuiaria thuja, in its primary state. Fig. 3,4. Th. ar„ 
ticulata, from a specimen in the collection of Mr Bean. 
PLATE XVI. Antennularia antennina. Fig. 2. represents the branched variety. 
