256 CTENOPIIOR.E. Part IL 



the same side ai^pear in profile near the anterior and posterior margin, encircling 

 in parallel curves the lateral ambulacra, but extending and gradually tapering all 

 the way down to the margin of the lobes. 



Our Bolina progresses rather slowly, its movements being tremulous, like dancing 

 in slow steps through tlie water, and now and then revolving upon itself. It 

 never performs those quick, darting motions which characterize Pleurolirachia, nor 

 does it exhiliit any thing like the graceful curves of the tentacles following like 

 a comet's tail in the wake of Pleuroljrachia ; for in Bolina the tentacles do not 

 extend beyond the margin of the lobes. And the lobes themselves, though the 

 principal organs of locomotion, are an impediment to quick and graceful movements, 

 the anterior and posterior ones being disproportionate in comparison to the size of 

 the body. There is, however, one attitude in which the movements of this animal 

 are exceedingly graceful : it is when the lateral IoIjcs are fully expanded, and even 

 recuived forward and Ijackward, and so elongated as to appear like the petals of a 

 flower spreading in opposite directions and curving outward. In this development 

 the animal generally reverses its position, the mouth Ijeing turned upward, and the 

 lateral lobes, also curved outward, present their vibrating fringes in the utmost 

 degree of activity, — the whole animal resembling an open white flower, with two 

 large and four small petals, revolving slowly upon its peduncle, or changing its 

 place in various directions. 



The ambulacra are so closely connected with the general appearance and the 

 movements of our Bolina, that it is appropriate to consider them in this relation 

 first. As in all CtenophoriV, they consist of vertical rows of locomotive flappers, 

 in every respect identical in their structure with those of Pleurobrachia, the differ- 

 ence consisting mainly in their extent. The pairs which run along the anterior 

 and the posterior sides of the body and extend upon the two large lobes, are by 

 fiir the longest, and also somewhat wider, their flapping combs tapering gradually 

 toward the abactinal area, so that the amlndacral rows terminate in points at 

 some distance from the central black speck. This is equally the case with the two 

 lateral jjairs of locomotive flappers, which, however, extend somewhat farther towards 

 the centre of the abactinal area. The tips of these eight rows of flappers encircle 

 the circumscribed area, which, liowever, extends far beyond, forward and backward, 

 between the rows of combs of the anterior and posterior pairs of ambulacra. 

 Another distinctive peculiarity of Bolina consists in the form of this side of the 

 body, which is not uniformly rounded, as in Pleurobrachia, l>ut somewhat depressed 

 along the longitudinal axis ; so much so that the two sides bulge sensibly above 

 tlie level of the central speck, while the anterior and posterior spheromeres are 

 on a level with it. The consequence of this prominence of the sides is that the 

 abactinal extremities of the anterior and posterior rows of locomotive flappers run 



