ACALEPHyE. 



171 



Cydippe. 



like the paddles of a propelling wheel, along eight equidistant convex 



bands, extending from near 

 one end or pole of the body- 

 to near the other, like the me- 

 ridians of an artificial globe. 

 The organs by which the Beroe 

 can attach itself to, or poise 

 its body on, a solid surface, 

 are two very long tentacles, 

 which are fringed on one side 

 with cirri. These cirrated ten- 

 tacles {d; d, Jig. 77.), which 

 can be stretched out in some 

 species to more than twenty times the length of the body, can be 

 instantaneously retracted into the two cavities or sheaths which 

 extend along each side of the slender intestine ; the marginal cirri 

 in this act being as instantaneously coiled up in a series of close 

 spirals, and the whole complex tentacles compacted within the limits 

 of a pin's head. 



" Like a planet round its sun, or, more exactly, like the comet with 

 its magic tail, our little animal moves in its element as those larger 

 bodies revolve in space ; but, unlike them, and to our admiration, it 

 moves freely in all directions, and nothing can be more attractive 

 than to watch such a little living comet, as it darts with its tail in 

 undetermined ways and revolves upon itself, unfolding and bending 

 its appendages with equal ease and elegance ; at times allowing them 

 to float for their whole length, at times shortening them in quick 

 contractions, and causing them to disappear suddenly, then dropping 

 them, as it were, from its surface, so that they seem to fall entirely 

 away, till, lengthened to the utmost, they again follow the direction 

 of the body to which they are attached, and with which the connec- 

 tion that regulates their movements seems as mysterious as the 

 changes are extraordinary and unexpected. For hours and hours I 

 have sat before them and watched their movements, and have never 

 been tired of admiring their graceful undulations. And although I 

 have found contractile fibres in these thin threads, showing that these 

 movements are of a muscular nature, it is still a unique fact in the 

 organisation of animal bodies, that by means of muscular action parts 

 may be elongated and contracted to such extraordinary and extensive 

 limits. At one moment the threads, when contracted, seem nodose ; 

 next, the spiral, elongating, assumes the appearance of a straight or 

 waving line. But it is especially in the successive appearances of 

 the lateral fringes, arising from the main thread, that the most 



