124 THE MEDUSAE. 



undoubtedly belongs, by the number and position of the gonads, as well as 

 by a peculiar radial arrangement of the tentacles described below, 



Tetrorchis erythrogaster, sp. nov. 

 Plate 29, figs 1-3. 



Station 4665 ; 300 fathoms to surface ; 1 specimen. 



Station 4675 ; 300 fathoms to surface ; 1 specimen. 



Station 4689; 300 fathoms to surface; 1 specimen. 



Station 4716; 600 fathoms to surface; 1 specimen. 



Station 4717; 800 fathoms to surface; 1 specimen. Type. 



Station 4721 ; 300 fathoms to surface ; 1 specimen. 



All the specimens are of about the same size, some 10-12 mm. in diame- 

 ter by about 8 mm. high ; and all have large gonads. They are in fair 

 condition, although the margins of all are somewhat battered. 



Bell. — Tlie bell is about two thirds as high as broad ; the gelatinous 

 substance very thick apically, though not forming a definite projection, 

 but thinner toward the margin. On account of this thickness the bell 

 cavity is shallow (PI. 29, fig. l). 



Tentacles. — The tentacles, all of which are solid, are interesting characters 

 of the species. The four opposite the four fertile radial canals are very stout 

 (PI. 29, figs. 1, 2), and provided with prominent entodermal roots. These 

 are the only perradial tentacles, for the remaining ones, which are much 

 smaller than those just described though resembling them structurally, have 

 no connection with the sterile canals. These small tentacles vary in num- 

 ber, but there are usually about three of them per octant. In all the speci- 

 mens the tentacles are broken short off, only the stumps remaining. In the 

 allied genus Persa, as well as in Aglaura and Aglantha, the tentacles are 

 more nvimerous and all of one kind, the differences in size in these genera 

 being without any radial significance such as connection with the radial 

 canals, but merely the expression of differences in age. I have been un- 

 able to find any otocysts; but from the condition in other Trachynemidae 

 it seems certain that some such structures are normally present in this 

 species, and that their apparent absence is due to poor preservation. 



Gastrovascular system. — The proboscis, which is cylindrical, about as long 

 as the depth of the bell cavity and with four inconspicuous lips, hangs di- 

 rectly from the subumbrella surface without any trace of peduncle (PI. 29, 



