18 EDWAKD T. BROWNE. 



The jelly of the umbrella is not only very thick, but very firm. There is no 

 apical depression in the wall of the umbrella, as found in S. nauarchus. The margin 

 of the umbrella is divided by grooves, which are opposite the tentacles, into 

 small lobes. 



The mouth has four short perradial lips, and the margin is arranged in slight 

 folds. Just inside the mouth there are four interradial, endodermal processes 

 somewhat triangular in shape. On the closing of the mouth these processes meet 

 and close the entrance to the stomach. One specimen is, however, abnormal, and its 

 mouth has seven pointed lips. It has five longitudinal ridges on the stomach. 



The most interesting features in this Medusa are the gonads and their position 

 with regard to the stomach. The stomachs of two specimens were cut into transverse 

 sections. One series (Plate II., fig. 4) shows ripe spermaries, and the spermatozoa 

 in the process of being discharged; the other series (Plate II., fig. 5) shows the 

 condition of the stomach after the gonads have been discharged. 



On the outside of the stomach there are four perradial longitudinal bands (fig. 2) 

 which slightly project as ridges. Inside each ridge runs a canal-like cavity lined with 

 endoderm (fig. 4). These canals branch out from the interior of the " mesenteries," 

 and are in direct communication with the top of the stomach and also with the radial 

 canals. They run down the wall of the stomach nearly to the mouth, and there 

 terminate blindly, without any communication with the exterior. 



Between the perradial bands on the outside of the stomach there are numerous 

 small holes (fig. 2). The shape of the holes varies in the different specimens, and they 

 may be either circular, oval, or somewhat quadrangular. The holes are arranged in a 

 single row on both sides of the perradial bands, and a few occupy the interradial spaces 

 in the upper part of the stomach. Within these holes, or protruding from them, is a 

 whitish flocculent substance, which is composed of spermatozoa. 



The sections show very clearly that the growth of the gonads has converted the 

 stomach into a reproductive organ, and that its function as a stomach has ceased. 

 There is practically no cavity for the reception and digestion of food, for although 

 a very small cavity does exist in the centre of the stomach (fig. 4), it is not in 

 communication with the mouth. In the lower part of the stomach the endoderm forms 

 a solid mass in the centre. 



The spermaries form globular or spherical masses encased in a very thin 

 membrane which lies next to the endoderm of the stomach. The endoderm, stained 

 with hsematoxylin, in the sections, has the appearance of a mosaic pavement in 

 different tints of blue. The cells have not a well-defined wall and are filled with a 

 rather dense homogeneous cytoplasm. The preservation is not good for cytological 

 details, and it must be borne in mind that the specimens were merely preserved for the 

 determination of the species. 



It is unfortunate that there are no intermediate stages of this Medusa in the 

 collection for the elucidation of the development of the gonads. The four perradial 



