CRUSTACEA. 9] 



the one-eighth of an inch in size, but whose destructive 

 powers have been manifested on many parts both of the 

 British and Irish shores. 



Some of the Crustacea possess luminous powers, and 

 together with the minute Medusae formerly mentioned (page 

 41), give to the sea the splendid phosphorescence described 

 by mariners. 



There is a singular race, which we have not yet mentioned 

 those which infest the skin, the eyes, and the gills of fishes, 

 and other marine animals (Fig. 64). Like the Entozoa, they 

 are parasites; but from they situation they occupy, not in but 

 upon other animals, they are spoken of by some naturalists 

 under the name Epizoa. They are crustaceous animals, under- 

 going transformations, and ere the brief period of their 

 locomotive state is ended, selecting the situa- 

 tion to which they afterwards adhere. Each 

 species is known as the parasite, iiot only of i 

 some one particular animal, but also of sorne| 

 one particular organ. Hence their number is 

 perhaps greater than that of the whole class of 

 fishes. The sexes are distinct, " The male 

 appears always to retain his freedom, and is 

 singularly smaller than the female, generally 

 not more than a fifth part of her size."* 



We shall close this brief notice of the struc- 

 ture, classification, and habits of the Crustacea, 

 by an extract from the Zoological Researches 

 of Mr. J. V. Thompson. It occurs in his de- 

 scription of the opossum shrimp, a species found 

 in " countless myriads" on some parts of our 

 coast, and so named from a singular pouch,Fig.G4. LE***A 

 analogous to that of the opossum, in which the ( MAGNIFIED >- 

 young are carried about. The spirit of this remark is, how- 

 ever, applicable to a wide range of objects. 



" It is in looking closely into the structure of these little 

 animals, that we sec the PERFECTION of the Divine Artist. 

 Nature's greater productions appear coarse, indeed, to these 

 elaborate and highly-finished master-pieces; and in going 

 higher and higher with our magnifiers, we still continue to 

 bring new parts and touches into view. If, for instance, wo 



* Owen's Lectures, page 149, &c. 



