REPORT ON THE DEEP-SEA MEDUSAE. 23 



In a more extended condition the extremely thin oral disk extends almost to 

 the margin, and shows eight small triangular lappets (four perradial and four inter- 

 radial, fig. 3, am) at the margin of the mouth. Eight narrow radial canals run from 

 the periphery of the bottom of the stomach ; these are united at the umbrella margin 

 into a circular canal, and the eight genitalia placed in their proximal third. 



The eight genitalia (four perradial and four interradial) are egg-shaped, thick-walled 

 sacs, pigmented red, and with the side walls touching each other ; they surround the 

 basis of the stomach like an eight-rayed star (fig. 2, s ; fig. 9, s). The sacs are half as 

 long as the oesophagus, occupying the upper half of the umbrella cavity, and contain a 

 large evagination of the radial canal (fig. 5, sc). A radial genital mesentery or meso- 

 gonium, a vertical radial fold with brown stains of the subumbrella, is inserted in the 

 middle of the subumbral wall of each genitalium ; this begins at the basis of the stomach 

 and runs along the subumbral median bine of the radial canals to the margin of the 

 umbrella (fig. 9, wr). These eight mesogonial leaves fasten the edges of the stomach, 

 halve the eight genitalia, and divide the space of the umbrella cavity into the eight 

 peripheric niches (or imperfect funnel cavities) above mentioned. The transverse section 

 of each genitalium shows that they actually consist of two completely separated halves, 

 between which the basis of insertion of the mesogonial fold (tor) is intersected as a 

 dividing septum. The living specimen examined by me in Pola was a male. The two 

 sperm-sacs of each genitalium (sm) were divided by a strong fulcral plate (2) from the 

 high cylindrical epithelium of the cndoderm (d), and lay immediately under the endoder- 

 mal epithelium, to which they owe their origin. 



Order IV. NARCOMEDUS^, Hasckel, 1877. 



Craspedotae with auditory clubs, which always stand freely on the umbrella margin, 

 with endodermal otolite cells. Ocelli at the basis of the tentacles usually wanting. 

 Tentacles inserted dorsally, connected with the distant umbrella margin by peronia 

 which divide it into a number of collar lobes. Genitalia originally in the lower or 

 oral wall of the stomach, from which they often extend peripherically into the radial 

 gastral pouches. Radial canals sometimes wanting, sometimes present, in which case 

 they extend in the form of flat, radial, gastral pouches. Annular canal sometimes 

 obliterated, but always divided by the radial peronia into a number of arched canals 

 bordering the margin of the collar lobes. Number of the radial parts (tentacles, 

 lobes, and pouches) indefinite and vaiying, rarely four, usually eight or more up to 

 thirty-two. Ontogenesis, as far as we know, usually hypogenesis, often accompanied 

 by metamorphosis. 



