THE CRASPEDOTB MEDUSA OLINDIAS AND SOME OF ITS NATURAL ALLIES. 15 



In the fully developed condition the gonads consist of numerous lobes, each of 

 which looks somewhat acinous, but a closer examination shows that these lobes are 

 continuous with each other; and a comparison with the lobed condition of the gonads 

 of Olindioides already described leaves no doubt that each gonad of Olindias must 

 have been formed as a single continuous thickening of the subumbrellar wall of a 

 radial canal and became lobed only secondarily. An examination of Haeckel's figure 

 ('79, PL XV, Fig. 10) of a young example of about 8 millimetres in diameter bears 

 out this view. 



As to the habitat of Olindias mulleri, I have not been able to ascertain it. Haeckel 

 ('79, p. 253) says that it appears to be rather rare, or perhaps to be confined to certain 

 localities, and I am informed by the authorities of the Naples Station that it occurs 

 especially in the months of October and November and then disappears. Consider- 

 ing that the exumbrellar tentacles are provided with adhesive disks, and judging 

 from analogy, it is very probable that Olindias mulleri is a bottom species like Olindi- 

 oides; and its comparative rareness must at least in part be attributed to this pecu- 

 liar habit. It appears, however, that the medusa can be obtained without difficulty 

 at the Naples Station in the proper season. The material lately sent me appears to 

 have been collected late in August or very early in September. 



IV. NATURAL RELATIONSHIPS OF THE DESCRIBED SPECIES. 



On looking through the published descriptions of the veiled medusa? it will at 

 once be evident to any one that the genera Olindias, Halicalyx, and Gonionema, and 

 the new genus Olindioides must be put together into a natural group, for which we 

 may adopt the name Olindiadae used by Haeckel. The common characters are very 

 simple and clear: jelly tolerably consistent, radial canals four or six, manubrium well 

 developed and quadrate, with distinct lips, velum well developed, gonads originally 

 a continuous fold of the subumbrellar wall of the radial canals, which may secondarily 

 become lobed, with two sets of tentacles, the velar and the exumbrellar, with an 

 adhesive disk somewhere on each exumbrellar tentacle, at the base of which there 

 is a pair of otocysts. The exumbrellar tentacles are provided with endodermal roots, 

 which more or less traverse the jelly to join the circular canal. Bottom species or 

 living among seaweeds. 



The genus Halicalyx, with one species, H. tenuis, was originally described by 

 Fewkes ('82) and recently redescribed by Mayer (: 00), who says that it is closely allied 

 to his genus Gonionemoides, but that it differs by the absence of "suctorial" disks on 



