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PROCEEDINGS OF THE 



[Dec, 1857. 



among Beroidae, also would constitute an analogy with its com- 

 plexity among Rhizostomidae. While the development of inter- 

 communicating tubes between the vertical ones, would be a further 

 development of a peculiarly Ctenophoran system. Also, if we 

 reason from analogy with Echinoderms, the tendency to dilatation 

 among Cydippidae is a sign of lower type than the tendency to 

 elongation among Beroidae. Thus both type and structural com- 

 plexity would combine to make the Beroidae a higher group than 

 the Cydippidae. 



EXPLANATION OF PLATE 14. 



Fig. 1 to 5. — Very young embryos of Bolina littoralis. 

 Fig. 1 — View with the tentacula in profile. 



c, the ambulacra. 



d, the digestive cavity. 

 m t the mouth. 



s, the sense-capsule. 1 

 t, the tentacula. 



Fig. 2 — View with the tentaculum turned towards the observer. Letters the 



same as in Fig 1. 

 Fig. 3 — View from above. 



a, one of the lateral sinuses of the circulatory system. The other letters 

 as above. 



Fig. 4 — View from above more magnified than the last. 



b, tentacular bulb; the lash is not figured. 



h, the external depression or chamber in which the tentaculum is situated- 



0, the elongate area, connected with the sense capsule. 



j?,the pointed projections of the wall of the lateral sinus a, which go to 

 meet the ambulacra. These projections did not appear to be yet tubular 

 at this stage. The other letters as in fig. 1 to 3. 

 Fig. 4 — View from the side : the tentacula, if figured, would have been seen [in 



profile as in Fig. 1. The letters d and s as in the preceding figures. 



g, g, incipient gastric tubes, just beginning to bulge downwards from the 

 central sinus of the circulatory system m. 



1, point where the lateral sinus approaches the surface to meet the ambu- 

 lacra which are not figured. 



m. part of the lateral sinus. 

 Fig. 6 — Magnified view of a portion of an ovary of Bolina littoralis. 

 a, external membrane or cuticle which supports, 



c, ciliary blades. 



m, muscular (?) masses. 



o, ovary in which the ova are seen crowded together. 



t, ambulacral circulatory tube. 



r, subjacent tissues. 

 Fig. 7 to 14 — Illustrating the fissiparition of Bolina littoralis. 

 Fig. 7 — Very young product of fission, without cilia. 



a, portion of the cuticle. See fig. 6, a. 



t, tentacular knobs beginning to sprout. 



