DESCRIPTION OF THE PLATES. 413 



PLATE III. 



Fio. 1. A diagram iiiteiuled to exhibit the sti-ucture of an Actinia, but 

 which must not be taken as strictly accurate, a is the base, h 

 the disk, c the tentacles, d the mouth, e the stomach, /,'/ and 

 k the septa dividing the cavity into chambers, on the free sur- 

 face of which are the grape-like masses of ovary, and in front of 

 the ovarj' the convoluted bands. (Copied from Sharpey.) 

 2. Represents a section of the A ctinia as seen in reality. The con- 

 voluted bands are seen covering the ovaiy, and terminating on 

 the inner wall of the stomach. (Copied from M. Hollard.) 



... 3. A magnified view of one convoluted band and ovaiy, with the 

 mesentery between them, as they appear when unfolded on the 

 gla.ss slide, previous to examination under the microscope. (M. 

 Hollard.) 

 4. Three Thread-capsules from an Actinia, greatly magnified ; one 

 with the thread still inside, the other two after the ejection. 



... 5. Vertical section of the Betlna of a Perch, showing the relative 

 positions of the pigment layer, the rods and cones, the granules, 

 fibres, and cells. (Copied from H. Miiller.) 



PLATE IV. 



Fig. 1. Campanvlaria. — The figure to the right is of the natural size; 

 that to the left is a branch greatly magnified. The Polype is 

 seen, flowerlike, expanding itself at the summit. An ovarian 

 capsule, to the right, contains Medusae in various stages of de- 

 velopment. (Copied from Van Beneden.) 



... 2. Plnmularia mi/riojjJu/llum, natural size. Five of the branches 

 are seen developed into ovarian capsules. 



... 3. Represents the spontaneous subdivision of one worm into two. 

 The head of the second worm is seen formed at the segment 

 whex-e the tail ought to be. (Copied from Milne Edwards.) 



PLATE V. 



Fig. 1. Lamprof/lena pulchella, one of the crustacean Epizoa, greatly 

 magnified, and seen from below. The figiu-e is copied from 

 Nordmann, with the addition of the ovisacs, not represented in 

 his plate, but which Burmeister, whose copy I possess, has 

 drawn in pencil. The Lamproijlnia is found in the gills of a 

 fish (^C)/prinus Jeses). 



2 N 



