AND SPECIES OF HYDROIDA. 281 



DESCRIPTION OF THE PLATES. 



[All the magnified figures, and many of those representing the species of its 

 natural size, are from drawings made from nature by the author. The figures 

 on Plate XXIII., and some of the other natural-size figures, are from drawings 

 by Mr. A. T. Hollick.] 



Plate IX. 



Figs. 1, 2. Perigonimus multicornis. 



1. Natural size. 



2. A portion, magnified. 



3, 4. Endendri'um rigidum. 



3. Natural size. 



4. A portion, magnified. 



5, 6. AmalthcBCt islandioa. 



5. Natural size. 



6. Magnified. 



7, 8. Mo7iocauhis groenlandiva. 



7. Natural size. 



8. Magnified. 



Plate X. 



Figs. 1-3. Hydraciinia monocarpa. 



1. A colony, natural size, growing over the shell of Trophon cla- 



thrafits. 



2. A portion of the colony, mag-nifled. 



3. Longitudinal section of one of the chitinous spines : a, external 



laminated layer ; 6, internal laminated layer ; c, axile cavity. 



4, 5. Podocorgne iiiermis. 



4. Natural size, spreading over the shell of Nassa reticulata. 



5. Portion of a colony, magnified. 



6, 7. Cladocorgnc pelagica. 



6. Natural size, growing over the surface of an air-vesicle of Sar- 



gassum bacciferum. 



7. Portion of a colony with hydranth and gonophores, magnified. 



Plate XI. 

 Figs. 1, 2. Campa7U(Iaria crcnata. 



1. Natural size. 



2. Mngnified. 



3. 4. Campan iilarla juncca . 



3. Portion of a colony, natural size. 



4. Portion, mngnifiwl. 



