REPORT ON THE DEEP-SEA MEDUSAE. 3 



regularly thinning out towards the margin. The exurabrella (or the external convex surface 

 of the umbrella) has a finely punctured appearance, as small round, stinging papillae are 

 scattered equally over it (fig. 1). The subumbrella (or the inner concave surface of the 

 umbrella) shows a strong annular muscular system, and eight narrow radial or longi- 

 tudinal muscles, of which four perradial (mj)) accompany the four radial canals, and four 

 interradial run in the middle between the radial canals (mi). Their proximal ends pass 

 into the longitudinal muscles of the stomach and the (Esophagus. The velum projects 

 from the umbrella margin towards the interior as a somewhat broad muscular membrane, 

 and narrows the entrance to the umbrella cavity considerably. The umbrella cavity 

 itself is flat and limited in size as the .central third of it is occupied by the large gastral 

 pyramid with the reproductive sacs. 



The umbrella margin is thickened into a roll, and pigmented red. At the points 

 where the four perradial canals open into the marginal circular canal, the rim of the 

 umbrella margin swells into four thick ocellar-bulbs with dark red pigment. Of these 

 the two opposite are without tentacles, whilst the two others, alternating with the former, 

 bear very long and strong tentacles (fig. 1). These are several times longer than the 

 diameter of the umbrella, cylindrical, thickened like a club at the base, and beset with 

 rings of thread-cells along the entire length. 



Gastrovascular system. The central part consists of the quadrangularly pyramidal 

 central stomach, in whose wall the reproductive sacs lie; and of the projecting oesophagus, 

 double the length of the central stomach, from whose basis spring the four rnultibranched 

 bunches of the oral styles. The peripheric part of the gastrovascular system consists of 

 the four perradial canals which spring from the basis of the central stomach and open into 

 the circular canal at the umbrella margin ; a canal passes from the latter into each of the 

 two tentacles, and traverses its whole length. These two tentacle canals, as well as the 

 four radial canals and the circular canal uniting them, are rather narrow and ribbon- 

 shaped, and show nothing special. On the other hand, the central part of the alimentary 

 apparatus has a somewhat complicated construction. 



The central stomach (figs. 1-3, gc) has the form of a quadrangular pyramid whose 

 height is nearly ecpial to the diagonal of its basis, and whose truncated end, which 

 has a downward direction, is the starting-point of the long oesophagus and of the four 

 tree-like oral styles. The quadrate basis of the quadrangular stomach pyramid occupies 

 the central third of the subumbrella, and is formed by the lower surface of the gelatinous 

 umbrella ; the four radial canals open into the central cavity at the four angles of the 

 square, and pass thence in the form of semi-cylindrical grooves to the four perradial 

 corners of the gastral pyramid. The thickened wall of these grooves forms the midrib of 

 the four leaf-shaped genitalia or pinnated "reproductive leaves." 



Genitalia. Each reproductive leaf forms an egg-shaped swelling, with the rounded 

 basis turned upwards and the truncated point turned down. As four to five deep transverse 



