[21] MEDUSJ5: FROM THE GULF STREAM. 947 



{dis. cent.) and a peri[)lieral corona, by a shallow coronal farrow {fos. 

 cor.). The exumbral wall of the former (dis. ceyit.) is horizontal, that of 

 the latter somewhat inclined to a perpendicular. Corona crossed by 

 thirty-two deep radial furrows alternating with the same number of ra- 

 dial rounded elevations {soc. sb., soc. ta.). The radial depressions alter- 

 nate with the marginal lappets ; the incisions on the bell margin between 

 the marginal lappets correspond to the radial elevations. 



The coronal region of the umbrella, which is the only portion of the 

 disk of this medusa which remains, indicates that this portion is rup- 

 tured easily from the central disk along the line of the coronal furrow. 

 The coronal furrow, howe\'er, has a shallow depth. From tlie resem- 

 blance of Nau])liantopsiii to Nauplianta the diameter of the discus centralis 

 is supposed to be about the width of the corona. The corona when seen 

 from the exumbral side (Fig. 2) is found to be composed of two zones, an 

 inner of gelatinous elevations alternating with radial furrows, and an 

 outer of leaf-like flappers or marginal lappets (Fig. 1, mg. Ip.). 



In the inner region (axial) the radial farrows extend wholly across 

 the exumbral surface of the corona alternating with the marginal lap- 

 pets, a furrow ending at the axial end of the medial line of each lappet. 

 The rounded radial elevations {soc. sb., soc. ta.), which lie between the 

 radial furrows, are sausage- like structures in half relief on the exumbral 

 surface of the corona. If the division of these elevations into socles of 

 the tentacles and those of the marginal sense-bodies be made, it will be 

 found that there are three contiguous tentacular socles {soc. ta.) which 

 alternate with a single socle of the marginal sense-body. 



The marginal lappets {mg. Ip.) are thirty-two in number and are rec- 

 tangular with rounded free angles. Their walls are very thin except 

 at the base, where they join the zone of the axial region of the corona, 

 after which they increase in thickness. The axial region of the corona 

 is formed of a confluence of the zones of the tentacles and that of the 

 sense-bodies, which are, as we have seen in Atolla, sometimes more dis- 

 tinct or difterentiated from each other. 



The tentacles which remain are long and flexible, arising from the in- 

 cision between the marginal lappets. In one instance three adjacent 

 tentacles were found, from which fact I was led to conclude that there 

 are twenty-four tentacles in all since there are thirty-two marginal lap- 

 l)ets, and I sui)pose there are eight marigiual sense-bodies. This rea- 

 soning is, however, based on the supposition, which accords with the 

 facts in other genera as far as known, that the diflerent sectors of the 

 disk of Nauphantopsis resemble each other. A live specimen may show 

 it to be false. When the corona is seen from the subumbral side we 

 see still additional evidences that the walls of the corona are at least as 

 perpendicular as in Peripliylla. Through the walls of the corona, looked 

 at from the subumbral side, the longitudinal radial depressions, which 

 are so pronounced on the walls of the exumbrella, are easily seen. The 

 surface of the walls of the subumbrella is, however, without protuber- 



