EXPLANATION OF THE PLATES. 



(11) 



and the oral arms are faintly visible below. This 

 figure shows distinctly, that in four directions the chy- 

 miferous tubes arise directly from the main cavity, and 

 in four other directions, alternating with the former, 

 they arise from the peripheric side of the sexual 

 pouches. 



Fig. 2. Magnified view of the margin of the disk, seen 

 from below, to show the origin of the tentacles a a, 

 between the lobules of the margin h h h, the veil 

 c extending along the under side. d represents a 

 chymiferous tube. 



Pig. 3. View of the same from above, more highly mag- 

 nified, showing the clusters of lasso-cells scattered over 

 the upper surface, a a tentacles ; b b lobules of the 

 margin ; c circular marginal chymiferous tube ; d d 

 radiating chymiferous tubes. 



Fig. 4. Longitudinal section of the margin of the disk, 

 the better to show the relations of the tentacles a a a, 

 and the marginal lobules b b. 



Fig. 5. "\'iew of the centre of the disk from below, the 

 oral appendages being removed, o pyramidal pro- 

 jection of the centre of the disk ; a b c radiating chy- 

 miferous tubes arising directly from the main cavity 

 of the body ; d d d radiating chymiferous tubes arising 

 from the peripheric side of the sexual pouches, one 

 of which, e, is laid open by the removal of its lower 

 floor, while in the others the floor is preserved ; i in- 

 dicates the arch over the opening leading into the 

 blind sac which extends below the sexual pouches. 

 This opening is generally represented as leading into 

 the sexual pouches, but this is not the case ; the arch 

 i supports a thin vein which separates the sexual 

 pouches from the blind sacs below. 



Fig. G. Top of a tentacle, magnified, e its cavity; a 

 epithelial layer covering its surface. 



Fig. 7. Termination of one of the oral appendages or 

 arms with its marginal fringes b, b ; tlie channel a 

 extends along its middle from the tip of the mar- 

 ginal lobes to the main cavity of the bodj-. 



Plate "VTIII. Profile view of our Aureba with structural 

 details. 



Fig. 1. Profile view, in a state of contraction of the 

 disk, when the oral ajipendages appear inclosed in the 

 cavity thus formed, and the sexual pouches are seen 

 in profile, exhibiting distinctly the wreath formed by 

 the sexual organs, as well as the origin of the chy- 

 miferous tubes arising from the margin of the sexual 

 pouches. 



Fig. 2. Transverse section of the margin of the disk, to 

 show the difference of thickness of the upper and lower 

 VOL. III. 40 



floors a and c, with the chymiferous tubes b b', formed 

 by the union of the two. 



Fig. 3. Similar section, magnified, a upper floor; c 

 lower floor ; b line of separation between the upper 

 and lower floors ; b' chymiferous tube formed by the 

 recession of the upper and lower fl(X)rs ; d lower sur- 

 face of the lower floor. 



Fig. 4. Upper surface of the upper floor magnified, to 

 show the clusters of lasso-cells scattered over it. 



Fig. .5. Transverse section of the margin of the disk, 

 wliich, in connection with fig. 4 of PI. VII., may fully 

 explain the relations of all the parts there combined. 

 a opening of the marginal circular chymiferous tube ; 

 e tlie tube itself; b section of the veil extending along 

 tlu^ lower surface; c part of the veil itself; d d ten- 

 tacles ; <l' cavity of one of the tentacles ; / radiating 

 cliymiferous tube, opening into the circular tube of 

 the margin ; y another radiating tube cut through in 

 the section, in which h marks the upper floor, and 

 f/ the lower surface of the lower floor. 



Fig. C. Magnified tentacles to show their connection with 

 the circular marginal tube, d tentacle; <Z' (/' cavity 

 of the tentacles ; e e marginal tube into which the 

 tentacles open. 



Fig. 7. Lobes of the ovary with their tentacles, a folds 

 of the sexual pouch ; b b ovarian lobes ; c c tentacles 

 of the ovarian folds. 



Fig. 8. An ovarian lobe, stretched out to show that the 

 folds of the sexual pouches surround the sexual organ 

 on both sides. a a folds of the pouch ; b b ovarian 

 lobes stretched ; c c tentacles of the ovarian folds. 



Fig. 9. Margin of the oral lobes, in the depressions of 

 which the eggs and planula; are received, magnified. 

 a a a clusters of eggs and planulfe in different stages 

 of development, gathered in the sac-like depressions 

 of the margin of the oral lobes, where they remain 

 until they are capable of living independently of their 

 ])arent ; b b the fringes or tentacles of the margin of 

 the oral lobes, adapted to seize upon the prey. 



Plate IX. Structural details of our Aureha. 



Fig. 1. Spermarian lobes stretched out, magnified sixty 

 diams. b b spermaries ; c c tentacles of the spermaries. 



Fig. 2. Several spermarian lobes, less extended, magni- 

 fied 1 2 diams. b b spermaries ; c c tentacles of the 

 spermarian fiilds. 



Fig. 3. Eye, with its chymiferous tubes and the tenta- 

 cles on its sides, o eye ; c e marginal circular tube, 

 from which arise the tentacle-like tubes /, /', c; fff 

 radiating chymiferous tubes ; d' d' tentacles opening into 

 the marginal tube. 



