138 DISCOPHOR^. Part III. 



SECTION II. 



THE GENUS STOMOLOPHUS. 



This genus is closely allied to Ehizostoma, and belongs to the same fixmily with 

 it; but it is easily distinguished by the manner in which the eight arms are soldered 

 together for their whole length, forming a large cylindrical tube, and leaving only 

 a small entrance into its interior, between its terminal lobes. The arms are so 

 closely imited in this cylinder, as seen in PI. XIV. Fig. 2, that it would be difficult 

 to distinguish them, Avere they not, in a measure, isolated at their end, 1", 2", 3", 

 4", which are the folded terminations of the four arms, visible from one side. 

 This apparatus is represented from different sides in PI. XIY. Fig. 1 shows only 

 its lower termination, the greater part of the central cylinder being hidden by the 

 umbrella, and the complicated terminations of the arms alone visible ; but Fig. 2, 

 which represents the Avhole cylinder, separated from the other parts of the lower 

 floor, shows the arms to be far more complicated in their termination than would 

 at first appear. Eight vertical ruffles are here presented, corresponding to the 

 duplicated angular projections of the terminations of each arm, two such ruffles 

 corresponding to each arm, 1 and 2 to the termination of the arm 1", 2 and 

 3 to the termination of the arm 2% 5 and 6 to the termination of the arm 

 3", and 7 and 8 to the tennination of the arm 4*. These ruffles are seen from 

 above in Fig. 3, which shows that each one of them is attached by a narrow base 

 to a projecting ridge of the cylinder, formed by the junction of the arms them- 

 selves, and each ruffle consists of two folds, the edges of which are themselves folded 

 and lobed. Their upper part. Fig. 5, a, is rounded, and their lower part terminates 

 in a prominent lobe, as this figure shows, which presents such a ruffle in profile ; 

 in Fig. 6 the same is represented from its outer surface, its two folded halves being 

 spread open. The manner in which the arms terminate shows in them also the 

 same disposition to divide into two distinct ruffles, only that here these ruffles meet 

 at the very end of the arms, while higher up, they divide into two horn-like pro- 

 jections, facing the ruffles above, from which they are separated by deep depressions. 

 But these projecting angles {h^ W h~ h^) are evidently the counterpart of the ruftles, 

 to which they coi-respond, and each horn is subdivided into two folds, corresponding 

 to the two folds of the ruffles, as Fig. 8 shows, in which a and b indicate the 

 less developed horns. Fig. 7 represents one of these terminations of the arms in 

 profile, h^ and a corresponding in this view to the parts marked by the same 

 letters in Fig. 8. Fig. 4 gives another view of these same parts, as seen from 

 below, the letters h}-, a, h-, b, corresponding to the same letters of Figs. 2, 7, and 8, 



