OF THE ACALEPIIS OF NORTH AMERICA. «J'^ 



cells, a, and the transparent margin consisting of small cells, b, b, and the projecting nettling cells at the tip of the 



branches, r, c. 



Fig. 27 represents a heap of such nettling cells. 



Plate III. 



This plate represents chiefly the muscles and nerves of Hippocrcnc superciVmris, all the muscles being printed blue. 



Fi". 1 and 2 represent the superficial muscular bundles. See p. 275. 



Fig. 1. a, a, b, b, c, c, bundles of vertical fibres ; d, d, connecting fibres between the upper and lower row of circular 

 fibres ; e,f, main vertical external bundles ; g, h, secondary vertical bundles. 



Fig. 2. a, a, circular fibres ; b, b, c, c, inner circular fibres ; d, d, main vertical bundles ; e, e, secondary vertical bun- 

 dles ; /,/, muscular fibres of the lower partition. 



Fig. 3 and 4 represent the inner muscles in two different views. 



Fig. 3. ./,(/, main vertical bundles; e,e,f,f, secondary vertical bundles; g, g, bundles of the radiating lubes; i, 



circular bundles. 



Fig. 4. b, b, c, c, double outlines of the circular fibres ; d, d, main vertical bundles; e, e,f,f, secondary vertical bun- 

 dles; ^?, o-,'bundles of the radiating tubes; /t, oblique fibres of the inner wall ; t, inner circular fibres ; A-, circular fibres 



of the lower partition. 



Fig. 5. Nervous system (see pp. 2G6 and 271) ; circular nervous cord below ; vertical threads following the radiating 

 tubes"; upper cord between the curves of the radiating tubes, with plexuses under their arches, and descending threads 

 midway between two radiating tubes ; all drawn in continuous dark lines. 



Fig. 6. The plexuses under the arches of the radiating tubes. 



Fig. 7. Seen from above, to contrast the outer and the inner systems of muscles ; a, a, the main vertical external bun- 

 dles U, c, the double outline of the inner circular system ; d, the main inner vertical bundles ; e,f, the secondary inner 

 vertical bundles; g, the outer secondary vertical bundles ; i, the inner circular fibres. 



Fig. 8. Also seen from above; but the inner vertical bundles less projecting; a, a, the outer main vertical bundles ; 

 b,b,lhe outer secondary vertical bundles; d,d,the main inner vertical bundles; i, the circular inner bundles; i, the 

 circular bundles of the lower partition. 



Fi-r. 9. Seen from above, the outer muscles being neglected ; b, c, the double outline of the inner circular bundles ; d, 

 the main vertical inner bundles; .,/, the secondary inner vertical bundles; i, the inner circular bundles ; ^^ the lower 

 partition ; m, the nervous cord ; o, the circular chymiferous tube. 



Fig. 10 and 11. Contractile cells in different states of elongation, with their nuclei. 



Fig. 12. Circular fibres of the lower partition. 



Fig. 13. The cells of the main nervous cord. 



Fig. 14. The lower partition, with a sensitive bulb ; a, sensitive bulb ; b, circular chymiferous tube ; c, nervous cord ; 

 d, radiating fibres of the lower partition. 



Fig. 15. Lower margin of the body; a, lower partition; b, nervous cord; c, circular chymiferous tube; d, vertical 



bundles of the outer wall. 



Plate IV. — Sarsia mirarilis. 

 The figures of this plate represent this species in various natural attitudes, as it is observed swimming through the 

 water, all the figures of natural size, excepting Fig. 1,2, 3, and 4, which are enlarged to show more d.stmctly the 



different parts. . . • i.. 



Fig. 1, 6, and 7. In attitudes of rest, when the gelatinous disk stands upright, and the four tentacles, stretched at right 



anaJs sideways from the lower margin, are bent suddenly, and hang loosely downwards. 



Fig. 1. The large proboscis hangs down beyond the lower margin of the disk. The connection of the four radiating 



lubes with the circular tube of the lower margin and the hollow tentacles is plainly shown. In Fig. 7, two of the ten- 



