372 CLASS CRUSTACEA. 



similarly prolonged, excepting in such females as lay their 

 eggs in holes or deep cavities. Now the females of the caligi 

 are not in this predicament. Miiller, and other zoologists, 

 have remarked, that these Crustacea can erect and agitate 

 these appendages. We think with Jurine the younger, and 

 such is also the opinion of his father, that they answer the 

 purpose of respiration, in the same manner as the filaments of 

 the end of the abdomen in apus. 



We find in the third volume of the General Annals of the 

 Physical Sciences, printed at Brussels, an extract from the ob- 

 servations of Dr. Surriray, on the fcetus of a species of caligus, 

 which he believes to be the elongatus^ and which is very com- 

 mon on the operculum of the esox helone. This naturalist 

 informs us, that having rubbed the two threads of the tail of 

 this crustaceous animal, he pushed out many transparent and 

 membranaceous eggs, each enclosing a living foetus, very dif- 

 ferent from the mother, and the description of which he gives 

 us. From these observations we might deduce, that these 

 filaments are sorts of external oviducts. But may there not be 

 some mistake in the case ? for I have studied, with some 

 attention, these same organs in several individuals, preserved, 

 it is true, in spirits, without having discovered a body of any 

 description in them. 



Some, whose feet are all free, and annexed, with the excep- 

 tion of the last two, to the anterior part of the body, {Cephalo- 

 thorax, Lat.) covered by the shield ; in which some at least of 

 the posterior feet are furnished with numerous and pinnated 

 filaments ; and in which the siphon is not apparent, have the 

 abdomen naked above, and terminated by two long filaments, 

 or by two stylets. They compose the subgenus 



Caligus (proper). Caligus risculus. Leach. - 



Caligus piscinus, Lat. ; Caligus curtus, Miill. Entomost. 

 xxi. 1,2; Monoculus piscinus, Lin. ; Caligus Mulleri, Leach; 



