3(> THE VOYAGE OF H.M.S. CHALLENGER. 



thidse is divided into many (10 to 20) bow-like or semicircular lobe canals, running on 

 the margin of the gelatinous lobes inside from the insertion of the velum, and opening 

 at the bases of the lobes into the periphery of the stomach. The circular canal is, how- 

 ever, in no way reduced but forms a spacious tube, whose lumen in the larger species 

 is often a millimeter in diameter and allows the introduction of a probe. Its 

 end'oderm is usually thickened and laid in folds, in some species even rising into 

 numerous tufts or papilke (like intestinal tufts). No such folds are recognisable in the 

 transverse section of the festoon canal in our Polycolpa forskalii, whilst in the species 

 immediately following a low annular fold is clearly present at the distal margin of the 

 canal as in Pedis (comp. PL VI. fig. 12, yc, and PI. XL fig. 12, yc). 



The reproductive glands in Polycolpa forskalii appear in their simplest form as a 

 broad circular girdle, occupying the largest part of the lower subumbral gastral wall 

 (fig. 1, sf; fig. 3, sf). In the living female specimen observed by me in the Red 

 Sea, this girdle was of a beautiful sky-blue colour, so were the tentacles and the urticat- 

 ing ring of the umbrella margin ; the points of the tentacles were dark-blue. The 

 subunibral convex external surface of the reproductive girdle is tolerably smooth, and 

 only traversed by insignificant and incomplete radial folds (fig. 1, sf). A thick com- 

 pressed mass of small egg-cells, between which isolated large ova are scattered, appears 

 in the radial transverse section (fig. 3, sf; fig. 4), between the high gastral endodermal 

 epithelium of the ova (fig. 4, dg) and the flat subumbral exodermal epithelium (fig. 4, 



Sub-family, Pbgasid^e, Hasckel. 



Peganthidfe, with a circle of several separate genitalia, forming dilatations of the 

 subumbral gastral wall and lying apart in the lobe cavities of the umbrella collar. 



Pegantha, 1 Hseckel, 1879. 



Peganthidae, whose gastral reproductive girdle is divided into a circle of separate 

 vesicle-shaped genital sacs, equal in number to the tentacles and alternating with them 

 (a simple or multi-lobed caecum in each lobe cavity). Numerous (10 to 30) collar lobes, 

 and the same number of alternating tentacles. 



The genus Pegantha represents the most complete and phylogenetically the youngest 

 genus of the remarkable famdy of the Peganthidaa, in which the famdy type reaches its 

 highest development. Whilst in the preceding genus Polycol'pa, the ancestral genus of 

 the family, the genitalium appears as a simple girdle in the lower wall of the stomach, 

 which, in Poh/ccnia and Pegasia develops into a peripheric circle of lobes, in 



1 Hnyti, a spring ; autln, a flower. 



