106 NEW INVERTEBRATA FROM 



Its bell is oblong, without a prominent apical protuber- 

 ance, although somewhat thicker in the apical region. The 

 lateral walls of the bell are of about uniform thickness and 

 are colorless. The outer surface of the bell has clusters of 

 nematocysts which are arranged in lines with regularity. 

 These structures have not the same prominence in the adult 

 as in the young. 



There are sixteen tentacles which are distributed as fol- 

 lows. At the end of each radial tube there is a single ten- 

 tacle, which is somewhat larger and longer than the 

 remaining tube. 1 Midway between these on the bell rim, 

 are four other tentacles approaching in size the radials, and 

 between these again small stumps, indications of eight 

 others. The length of none of the tentacles is more than 

 half the height of the bell. 



The bases of the tentacles bear reddish patches of color, 

 and a conspicuous black pigment spot which indicates the 

 position of the future ocellus. These tentacular bases lie 

 immediately upon the marginal vessel, while the short tube, 

 which connects the cavity of the base of the tentacle in an 

 adult with that of the marginal vessel, is not developed. 

 There are no otocysts or structures which can be compared 

 to them. 



The radial tubes are four in number. Each tube is broad, 

 with indications of the lateral appendages appearing as 

 simple zigzag notches in the gelatinous wall of the tube. 



The sexual glands are not developed, but at the very 

 base of the proboscis there are two small buds, just below 

 the union of the proboscis with the inner wall of the bell. 



*It is probable that when the Polyorchis buds from its hydroid it has four radial 

 tubes, four tentacles and possibly the stumps of four similar interradial append- 

 ages. As the radial tubes at that time lack lateral branches, we have in this stage 

 a medusa closely resembling the young Sarsia. If my suppositions are correct, 

 there seems no doubt that Polyorchis belongs to the true Anthomedusae, and that 

 it is allied to Sarsia. The rows of meridionally placed nematocysts on the outer 

 bell wall are suggestive in this interpretation. 



