246 BRITISH ENTOMOSTRACA. 



the Argulus referred to one species, which seems pretty 

 generally diffused over Europe. 



In 1837 [Messrs. Herrick and Dana described another 

 species in the ' American -Journal of Science and Arts' for 

 that year. It was found in Mill River, AVhitneyville, prey- 

 ing upon the fish called the Sucker, a species of Cato- 

 st 01 n us. The description of this species was accompanied 

 with most elaborate anatomical details, and illustrated 

 with numerous good figures. They gave a very accurate 

 description also of the young or imperfect animal. Various 

 other notices of the Argulus have been published since 

 that. A short account of the common species was inserted 

 by Mr. Thompson, of Belfast, in the ' Annals and Maga- 

 zine of Natural History' for 1839, vol. v, with a very in- 

 teresting account of the habits of the little creature, as 



observed by himself in an individual taken alive at Belfast. 



" 

 and kept by him for some time ; and in the ' Memoirs of 



the Helvetic Society' for 1845, M. Vogt has given some 

 very interesting details of the same species, with good 

 figures, illustrative of some parts of its anatomy. A third 

 species has been described by Mr. Gould, in his ' Inverte- 

 brataof New York,' under the name ol\ //Y//////.V <7/Wr, and 

 more recently, a fourth species has been added to the list 

 by M. Lucas. It was found by him in Algeria, and is 

 figured in the recent 'Exploration scientiiiqiie del'Algerie/ 



Anatomy and Physiology, $'c. The body of the Argulus 

 is covered by a carapace of a greenish hue, and nearly 

 transparent. It is slightly convex, obtusely rounded in 

 front, and deeply notched behind. This deep notch is 

 occupied by the thorax, which at first sigh I almost escapes 

 observation, the animal apparently having the cephalo- 

 thoracic portion of the body covered altogether by the 

 broad carapace. This may be divided into three parts. The 

 lir-t. or anterior, is rounded in front, and prolonged behind, 

 terminating in a blunt point. The other two, the posterior 

 portions, ;irc of mi oval form, and cover the lateral parts 

 of the animal. They arise towards the middle of tin 



