: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, Whitney ville, prey- 

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

 stomus. 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 tlie 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 1889, 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 descril)ed by Mr. Gould, in his ' Inverte- 

 brataof New York,' under the name oi Argulus alosa\ 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 scientifique de F Algerie.' 



Anatomy and Physiology, 8fc. — 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 sight almost escapes 

 observation, the animal apparently having the cephalo- 

 thoracic portion of the body covered altogether by tlie 

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

 first, or anterior, is rounded in front, and prolonged behind, 

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

 portions, are of an oval form, and cover the lateral parts 

 of the animal. Thev arise towards the middle of the 



