314* CONTRIBUTIONS TO THE NATURAL HISTORY 



tacles are left out, to show more plainly this connection and the connection of the radiating tubes with the central cavity 

 and the proboscis. 



Fig. 2. As seen from above, ihe proboscis being retracted and coiled up within the main cavity of the disk. Here, 

 also, the connection of all parts is plainly shown, and the outlines of the interior muscular system well defined. 



Fig. 3. Seen from below, the tentacles being cut near their base. 



Fig. 4. A six-rayed variety of the same species, seen from al)ove, the tentacles being also cut near their base. 



Fig. 5. A specimen in a state of contraction, seen obliquely from above, the tentacles contracting into irregular undulations. 



Fig. 6. In a state of rest, the tentacles, however, to some extent contracted, and much shorter than in Fig. 8, 11, and 

 12, in which they are fully developed. 



Fig. 7 gives a similar aspect, only the lower margin is contracted, while in Fig. 6 it is more expanded, so that in 

 Fig. 6 the outline is hemispherical, and in Fig. 7 more globular. 



Fig. 8. A specimen in a state of contraction of its lower marign, the gelatinous disk being elongated, and the animal, 

 the tentacles of which are in the utmost state of elongation, turning upon itself, so that the tentacles are curved iu 

 graceful arches, and the proboscis drawn in. 



Fig. 9. The body has assumed a more globular appearance, the tentacles are slioitened, and the proboscis hangs out, 

 the animal moving horizontally. 



Fig. 10. The hemispherical disk is somewhat elongated, the proboscis hangs out, and the tentacles are still more shortened. 



Fig. 11. The six-rayed variety swimming obliquely, with its tentacles fully developed and the proboscis curved inwards. 



Fig. 12. Another specimen of the common variety swimming downwards, the tentacles elongated, but not in their ut- 

 most state of elongation, the proboscis also drawn in. 



Plate V. 



This plate represents structural details of Sarsia mirafiilis. 



Fig. 1, 2, 3, 4, 5, 6, and 11. The muscular system chiefly is represented, in blue color, but the radiating tubes and the 

 circular tube, as well as the proboscis, are also more or less distinctly seen ; in Fig. 1, 2, 3, 4, 5, and 6, the proboscis, 

 however, is suppressed, not to crowd the figures. 



Fig. 1. The inner muscular systems; d, d being the main vertical bundles; e,e,f,f, the secondary inner vertical 

 bundles; g, g, the radiating tubes ; and (, the circular inner bundles. In this state of contraction, in which the muscles 

 are best seen, the circular tube of the lower margin appears as a quadrangular figure, contrasting most remarkably 

 with its circular outline in a natural position, as shown in Fig. 11. 



Fig. 2. The same, seen from below, so that the sensitive bulbs, with the eye-specks and tentacles, are well seen ; </, d 

 represent the main vertical inner bundles ; e, e, f,f, the secondary muscular vertical bundles ; g, g, the lower partition ; 

 i, i, the inner circular bundles ; /, /, the tentacles ; and o, o, the accessory bundles of the vertical tubes. 



Fig. 3 shows the outer muscular system ; a, a being the main external vertical bundles ; b, h, the secondary external 

 vertical bundles; all of which are united above by circular fibres, as are also the secondary bundles somewhat lower down ; 

 g, g, radiating tubes. 



Fig. 4. The same muscles, from below ; a, a being the main external vertical bundles ; i, b, the secondary external 

 vertical bundles ; g, g, the lower partition ; /, /, the tentacles. 



Fig. 5. The same parts with the internal muscular systems in a specimen of the six-rayed variety ; d, d being the main 

 external bundles, confounded with the main internal bundles ; e and f, the secondary internal bundles ; g, g, the lower 

 partition. 



Fig. 6. The muscular system iu the utmost state of contraction, so that the outline of the animal appears four-lobed 

 and the inner main cavity eight-lobed ; d, d being the main external bundles ; e, e,f,f, the secondary internal bundles. 



Fig. 7. The proboscis in its connection with the central digestive cavity, the radiating tubes, the circular tube, and the 

 tentacle ; o being the mouth ; a, the lower part of the proboscis ; b, its middle part covered with eggs ; and c, its upper 

 part ; d, indicating the central digestive cavity ; c, the radiating tubes ; f, the sensitive bulb ; and ;', the eye-speck. 



Fig. 8. The proboscis in another attitude ; o being the mouth ; a, b, c, d, corresponding to the same letters in Fig. 

 7 ; but in this figure there are no eggs ; e, outer coat ; i, inner coat. 



