REPORT ON THE DEEP-SEA MEDUSAE. 35 



6, cf; fig. 8, cf). The latter runs like a garland along the margin of the lobes and opens 

 throughout between every two tentacles with a double mouth in the periphery of the 

 stomach. The stomach is a completely flat, circular, or polygonal pouch, occupying the 

 entire lower surface of the umbrella lens (fig. 3, gc). Corresponding to the latter, the 

 upper wall or cover of the stomach forms a flat or only slightly convex, rarely concave, 

 circular surface, whose periphery presents in certain conditions of contraction a regular 

 polygon ; each of its projecting corners corresponds to a tentacle insertion, each side 

 of the base to the base of a collar lobe. The projecting corners sometimes form 

 triangular pouches with the ends directed towards the insertion of the tentacle (last 

 rudiments of radial pouches). The lower wall or bottom of the gastral pouch is a 

 circular or regularly polygonal thick, muscular plate, covered with endoderm above and 

 exoderm below. The oral opening, which is extended into a short cylindrical oesophagus 

 hanging freely down, is in the centre (fig. 3, at). The thickened oral margin is simple, not 

 split up into oral lobes. The muscular plate appear considerably swollen at the oral 

 margin (longitudinal section, fig. 5, m). Numerous gland cells (gd) are scattered 

 between the high cylinder cells of the gastral endoderm (dg), they are 2 to 3 times 

 as broad as the latter, have twice as large a nucleus, and are distinguished by the turbid, 

 granular nature of the protoplasm. As in all Narcomedusae, the muscular wall of the 

 stomach is capable of considerable contraction and dilatation. 



The pecuhar festoon canal (" canalis festivals," fig. 6, cf; fig. 8, cf) which attains its 

 highest development in the Peganthidae and the complete want of radial canals con- 

 nected with it, suffices alone to characterise this family and to distinguish it from all 

 other Medusae. Phylogenetically this peculiar condition is simply derived from that of 

 the Cunanthidaj, and from the fact that the stomach stretches by peripheric growth as 

 far as the insertion of the tentacles (or to the limit of the umbrella lens and the umbrella 

 collar), and so includes the broad pouch-shaped radial canals. The deep sinuses which 

 are found in the Cunanthidas between each two radial pouches are in some measure 

 obliterated in the Peganthidae. Hence the " triangular points " of the periphery of the 

 stomach, which in some Peganthidae run out to the insertion of the tentacles (already 

 described by Eschscholtz in Polyxenia as " long three-sided processes of the stomach "), 

 must, in fact, be considered the last rudimentary remains of radial canals. While in the 

 Cunanthidaa the latter still serve to connect the stomach with the radial canal, in 

 Peganthidae the triangular points open into the periphery of the stomach in as many 

 places as there are insertions of the tentacles between each two collar lobes. The circular 

 canal has, therefore, the same disposition as in the nearly related Cunanthidae ; it 

 runs along the velar margin of the collar lobes immediately under the urticating ring 

 of the true umbrella margin ; it is, however, interrupted at the basis of each two ad- 

 jacent lobes by the insertion of the tentacle, and opens into the stomach beside the 

 latter. The state of the case may be expressed thus : the annular canal of the Pegan- 



