CYDIPPE PILEUS. 119 



stitute the generative apparatus. In some individuals these folded 

 membranes enclose the ova, and in others contain a fluid filled with 

 spermatozoa ; so that they evidently represent the ovaria and testes of 

 these Acalephs. 



(308.) CILIOGEADA. In the Ciliograde Acalephce (CTEJ^OPHOEA), the 

 organs of motion consist of narrow bands of vibratile cilia, variously 

 disposed upon the surface of the animal. 



(309.) In the globular forms of the Beroes (fig. 58), these cilia are 



Fig. 58. 



1. Cydippe pileus : a, tentacula unfolded. 2. Supposed nervous system. 3, 4. Isolated cilia. 



arranged in eight longitudinal rows, and appear to be attached to sub- 

 jacent arches of a firmer consistence than the rest of the body. They are 

 generally quite naked, but in Pandora are lodged between folds of the 

 skin, which afterwards close over and completely conceal them ; their mo- 

 tion is extremely rapid, and sometimes only recognizable by the currents 

 they produce, or by the iridescent hues that play along the arches. 



(310.) The arrangement of the locomotive apparatus appended to 

 the eight longitudinal costal bands is extremely beautiful. The series 

 of vibratile fringes is attached to a row of minute transverse ridges, 

 disposed almost like the steps of a ladder, and, moreover, in their essen- 

 tial structure they differ very materially from vibratile cilia of the 

 ordinary character. In shape they are not filiform, but resemble 

 membranous laminae deeply fringed around their free margin, having 

 the shape of so many little semi-oval palletts. The movements of these 

 flabelliform appendages are very rapid, and are seldom interrupted while 

 the animal is in vigorous health ; the slightest contact, however, is suffi- 

 cient to stop them. The different laminae, moreover, belonging to the 

 same row are quite independent of each other ; neither does interference 

 with one produce the slightest effect upon the action of the rest. The 

 animal, nevertheless, seems to possess the power of arresting or con- 

 trolling their motions at pleasure. It is likewise remarkable that the 

 vibratory movement is kept up for a very long time in fragments sepa- 

 rated from the rest of the body, without at all changing its character ; 



