TRACHYMEDTJS.E — PTYCHOGASTRIA. 375 



elongate, 4-sided prism, the mouth projecting slightly beyond the velar opening and pro- 

 vided with 4 simple lips. The 8 radial and interradial, radiating ridges of the exumbrella are 

 red, with an expanded red spot at the margin. There is a yellow spot on the exumbrella at 

 each of the 16 notches of the 16 marginal lappets. The suckers of the tentacles are tipped 

 with red. The entoderm of the stomach is golden-yellow and the gonads are red. The sub- 

 umbrella contains some brown pigment. 



Haeckel found a single male specimen of this medusa between 200 fathoms and the sur- 

 face near Pola in the Adriatic Sea, and later the Challenger dredged one from between 600 

 fathoms and the surface in the entrance to the Straits of Gibraltar. Haeckel, 1881, presents 

 beautiful figures of the medusa. 



Ptychogastria antarctica Browne, Maas. 



Pedis antarctica, Haeckel, 1879, Syst. der Medusen, p. 266; 1881, Report Challenger Expedition, Zool., vol. 4, p. 15, plates 5, 



6; figs. 1-20. 

 (Ptychogastria ?) antarctica, Browne, 1903, Bergens Museums Aarbog, No. 4, p. 29. 

 Ptychogastria, Maas, 1906, Fauna Arctica, Bd. 4, Lfg. 3, p. 493, Jena. 



Bell 36 mm. wide, 24 mm. high. Apex thick-walled and dome-like, separated by a deep, 

 annular furrow from the thin-walled, flaring, lower part of bell. The exumbrella is traversed 

 from margin to apex by 5 rib-like thickenings; 500 to 600 of these furrows at margin and 32 

 more prominent, radial ribs running the whole length, and 32 less prominent ridges alternating 

 with them. Gelatinous substance thick in dome, but thin in the flaring side walls below 

 annular furrow. It is especially thick at apex of dome, where it sends a conical projection 

 downward into stomach-cavity. 



Bell-margin thickly beset with several rows of tentacles and suctorial disks arranged in 8 

 larger and 32 smaller groups; and alternating with these in position and arising from the 

 exumbrella, some distance above the other groups, are 40 large, isolated "suckers."* Each 

 smaller group of marginal appendages consists of an upper cluster of 16 to 20 short-stalked 

 "suctorial cups,"* and below these are 12 to 16 tentacles, which may or may not terminate in 

 a sucker. The entoderm of these tentacles is composed of solid chordate cells. Most of the 

 tentacleswere broken off" in the specimen studied by Haeckel. The 8 to i6( ?)lithocysts lie on 

 the axial side of the bell-margin under the velum, inside of the lowest row of marginal tentacles. 



The velum is so wide that it can probably completely close the bell-opening. It is pig- 

 mented and its subumbrella side contains powerfully developed ring-muscles. There are 8 

 radial-canals, and a ring-canal which gives off" 1 1 to 13 short, blindly ending, centripetal 

 canals in each octant; of these 3 are large and 8 to 10 are smaller. These centripetal vessels 

 are straight and simple and taper to pointed ends. 



The manubrium lacks a peduncle and is about half as long as the depth of the bell- 

 cavity, and its mouth is 4-sided and provided with 4 flaring, muscular lips. Longitudinal 

 muscles extend down the manubrium to the 4 radial angles of the lips, while between them 

 there is a powerfully developed system of circular muscles. The stomach gives rise to 16 

 evaginated, hollow pouches arranged in pairs on both sides of 8 longitudinal furrows which 

 extend down the adradii of the stomach to the zone of the 16 pouches, which are only a short 

 distance above the mouth-opening. Between each pair of evaginated pouches in each of the 

 8 adradii there is a sharp-pointed conical invagination of the stomach-wall. The 8 swollen, 

 folded, oval gonads occupy the proximal halves of the 8 radial-canals near periphery of stomach, 

 with which they are connected by 8 poorly developed mesenteries. The ectoderm of sub- 

 umbrella contains dark violet-brown pigment, through which the 8 radial-canals stand out as 

 milk-white lines. 



A single specimen was found by the Challenger Expedition in the Antarctic Ocean, S. S. E. 

 from Kerguelen Island, at a depth of 1,260 fathoms. 



♦These so-called "suckers" and "suctorial cups'* are doubtless only broken tentacles. 



