8 



MEDUSA. I. 



so that there are four triangular pouches between the dorsal wall of the stomach and the subumbrella 

 (see the textfig. 3, which is a copy of a drawing made from a specimen from the "Michael Sars" and 

 destinated for my paper on the material of that expedition). The mouth-tube is quadrangular, very 

 wide. The edge of the mouth is somewhat crenulated, and the corners are a little dilatated, forming 

 four short, simple lips. The length of the manubrium is variable ; it never reaches the opening of the 

 bell cavity, and in most specimens its length is less than ^j^^ of the depth of the bell-cavity; this 

 variation may depend on the state of contraction. There are four radial canals. The proximal part 

 ('/a— ^/s) of each radial canal is wide and contains the gonads, the distal part is straight and narrow 

 and communicates with the narrow circular vessel. The proximal part of the radial canal is funnel- 

 shaped, communicating with the stomach by a perpendicular .slit, somewhat broader at the top than 

 at the bottom. A transverse section of the gonadial part of the radial canal is pear-shaped in the 



proximal part, nearly circular in the distal part. The 

 line along which the gonadial part of the canal is 

 attached to the subumbrella sends out a number of 

 short lateral branches, so that the attachment of the 

 dorsal wall of the canal has the .shape of a pinnate 

 figure (Plate I, fig. i and textfig. 3). Occasionally this 

 figure is somewhat irregular, or it may be more or less 

 zig-zag-shaped. Each of the radial canals contains two 

 rows of sack-shaped gonads, attached to the dorsal wall 

 of the canal in the spaces between the above-mentioned 

 lateral branches of the line of attachment and hanging 

 down into the cavity of the canal. The surface of a 

 gonadial sack is covered with a thin entodermal epi- 

 Kig. 3 a,roma/o>ie„m rubrum Fewkes, seen obliquely tlielium (see Plate I, figs. c, 6, 7, and 8), and each sack 



from the top. ^ ' & O) > / ) /' 



has a narrow ectodermal lumen communicating with 

 the bell cavity through a fissure in the dorso-lateral wall of the canal (Plate I, figs. 4, 6, and 8). In 

 view of the scarcity of room, the gonads of the two sides of the canal are more or less regularly 

 alternating (Plate I, figs. 5 and 6). The number of gonads varies from 10 to 16 on either side of 

 the canal. The side-walls of the canal are, as a rule, tightened closely over the gonads so that the 

 wall becomes faintly lobed or undulated. In the upper part of the lateral walls of the canal (outside 

 the gonads) the entoderm consists of one layer of cubical or cylindrical cells (Plate I, figs. 5 and 7). 

 In the funnel-shaped part of the canal the lower parts of the lateral walls, which are not pressed 

 by the gonads, are covered with a thicker entoderm, consisting of several layers of cells (Plate I, 

 fig. 7); evidently the digestion of the food takes place in this part of the radial canal. In larger speci- 

 mens some of the proximal gonads are frequently developed in the dorsal wall of the stomach on 

 either side of the cross-arms. 



There are about 20—24 solid tentacles, all of the same shape and size; the tentacular bulb is 

 hollow, conical, with a heart-shaped base. There is no trace of a basal spur. The tentacles may be 

 spirally coiled (Plate I, fig. 2). In a contracted state the tentacles are deeply and closely trausversally 



