MEDUSA. 155 



is a well developed system of circular muscles which forms a ring, the outer 

 circumference of which meets the bases of the tentacles, while the inner 

 edge coincides in position with the middle points of the gonads. In addition 

 to these circular muscles there are sixteen strands of radial muscles which 

 extend outward on either side of the gonads to the middle of the lappets. 

 There are also eight radial muscle strands in the ex-umbrella which extend 

 outward toward the sense organs, and in addition to these there are eight 

 well developed groups of radial muscles at the bases of the eight tentacles. 

 The stomach consists of a wide lenticular space at the centre of the disk, 

 and this gives rise to eight radial pouches extending outward in the radii of 

 the eight sense organs. Each of these pouches bifurcates and sends a pair 

 of branches into the lappets, making in all sixteen terminal pouches. The 

 bell is translucent and milky in color. The ocelli and gonads are of a rich 

 brown color, and the entodermal core of the gastric cirri are dark blue. 

 Two specimens, one male and the other female, were found at night on the 

 surface south of Rangiroa Island, Paumotus, on September 24, in S. lat. 

 15° 22', W. long. 147° 57'. 



Nausithoe punctata var. pacifica Agassiz and Mayek. 



Nausithoe punctata var. pacifica Agassiz and Mayer, 1899 ; Bull. Mus. Corap. Zool., Vol. 

 XXXII., p. 170. 



Plate 7, fig. 3<2. 



The disk is quite flat and is about 4 mm. in diameter. There are 

 eight solid tentacles which are quite rigid. These tentacles are each 

 about three-quarters as long as the bell-diameter. They arise from sockets 

 on the sub-umbrella edge of the disk. There are sixteen sharply cleft 

 marginal lappets, two between each successive pair of sense organs. 

 The eight sense organs alternate in position with the eight tentacles, and 

 are situated at the bottom of the niches between the lappets. Each 

 sense organ contains a centrifugal otolith and a centripetal dark-brown 

 ocellus. Eight gonads lie in the eight tentacular radii. In the female 

 the ova are large and prominent. The mouth is a simple cruciform 

 opening in the centre of the sub-umbrella, the arms of the cross, passing 

 through two of the tentacular diameters. There are four groups of gastric 



