Seminal Fluid and Organs of Generation in the Crustacea. 185 



out any appearance in the primary cells of the enclosed bodies, being like 

 these Filaria. This, of course, also extends to M. Kollikcr's observa- 

 tions on the same fluid in Cirripeds, for they must be looked upon now 

 as Crustaceans also.* 



As the ova pass through the spermatheca, they come in contact with 

 the spermatozoa, and in this way are impregnated. They also appear 

 to obtain in this organ a thick coating of albumen, which afterwards be- 

 comes the ovisac. 



The organs employed in this class of animals for the proper defence 

 of the ova, after they have been excluded from the ovaries, and during 

 the time they are attached externally to the mother, are very interest- 

 ing. After a careful analysis, they will be found throughout the whole 

 class to be either legs not fully developed, or parts of these organs very 

 much developed. The first of these divisions will be found to exist in 

 the higher Crustacea, such as those belonging to the Brachyura, the 

 Anomoura, and Macroura ; this form is also found in the Araneiformes. 

 It is in the Stomapoda we first observe these organs assuming another 

 character, namely, that of protecting scales. We find this character gra- 

 dually making its appearance, however, in the lower Macroura, as in 

 Hippolyte and Palsemon, where we find the ova attached by means of 

 filaments to broad scales, and in the other genera ; if this is not present, 

 the usual armature of the body will be observed enormously developed, 

 so as in some cases almost to meet, by means of their edges, on the ab- 

 dominal surface of the body. 



In the Amphipoda, Lsemodipoda, andlsopoda, we find these ovigerous 

 scales bearing a considerable resemblance to those of the Stomapoda. 

 In the Branchiopoda this character still exists, but in rather a more in- 

 teresting form. In Apus we find the ova contained in a cavity formed 

 by the expansion of the first joint of the eleventh pair of legs into two 

 large circular-shaped and hollow plates, which, when closed together, 

 form a safe means of defence. Through the genera Branchipus, Artemia, 

 &c., we are led to Daphnia, Polyphemus, and Evadne, where we find 

 this means of defence in its maximum state of developement, namely, 

 one, or perhaps more, pairs of legs enormously developed, so as not to 

 cover the ova only, but the whole body. The occurrence of this in 

 these animals, is the cause of their unusual and grotesque appearance. 

 From this form we are more suddenly brought through Saphirina and 

 Cetochilus to the Monoculi, where we find a difierent means of defence 

 altogether. Instead of great developement of the feet, we find one 

 pair, or perbaps more, of these organs aborted altogether, and sacs or 

 bladders are secreted each time the animal becomes loaded with spawn. 

 This form is carried into, and continued throughout all the Siphonos- 

 toma, until we reach the Araneiformes, where we again find these or- 

 gans assume almost the same appearance as those with which we first 



* Edinburgh New Philosophical Journal for July 1843. Vol. 35, p. 88. 



