186 
BRITISH ENTOMOSTRACA. 
seems to be ignorant of his discoveries, though the work 
of Ramdohr preceded his by fifteen years. 
Gunner,* * * § Strom, f Tilesius, J Viviani, § &c. had all 
noticed or described various species, previous to Jurine’s 
time, and several new species have been described since ; 
but, subsequently to his history, no work has been exclu- 
sively devoted to the Entomostraca. 
Mr. Templeton, however, has added several new species 
belonging to this family, which he discovered within the 
tropics, and Koch has described a good many in Germany, 
while M. Milne Edwards has bestowed much pains in 
elucidating their systematic arrangement. 
Lately Mr. Dana has added a great many species, dis- 
covered by him during the American voyage of exploration 
under Captain Wilkes, and has described them in the 
Proceedings of the American Academy of Arts and 
Sciences’ for 1847 and 1849. 
Anatomy and Physiology, 8fc . — The body of the animal, 
which is soft and gelatinous, is inclosed within a horny 
shell, which covers it like a buckler, but opens interiorly 
to give issue to the antennae, organs of the mouth, and 
feet. In general the thorax and abdomen are pretty 
easily to be distinguished from each other, and are com- 
posed of about ten segments, the thorax usually having 
four, and the abdomen six. In the upper or cephalo- 
thoracic segment, which is usually much the largest of all, 
we find the eye, the antennae, mandibles, mouth, a pair 
of foot-jaws, and one pair of feet. 
The eye is situate near the upper extremity of this first 
segment, and in the centre. It is tolerably large, and is 
single, and in some, as in the Diaptomus Castor , we can 
perceive the muscles which move it, of which there are 
several. The antennae are four in number. The superior 
* Skrifter som udi det Kiobenhavnske Selskab., Deel x, 1765. 
f Ibid., Deel ix, 1765. 
X Memoires de l’Acad. Imper. des Scien. de Petersbourg, v. 
§ Pkosphorentia Maris, &c., 1805. 
