THE MEDUSA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 241 



of warts (Gallertperlen) on the marginal lobes. In the Scotia specimen the warts are 

 quite conspicuous upon the lobes. Some of the lobes have nine warts (four on each 

 side and one in the middle), agreeing in number, position, and size with Vanhoffen's 

 description. Many lobes, however, have only seven warts (three on each side and one 

 in the middle), and as the two smaller uppermost warts are the missing ones, these 

 lobes are probably at an earlier stage in development. The central wart was missing 

 in two lobes — perhaps an instance of variation. 



There are twenty-four tentacles and twenty-four sense-organs. The gonads are 

 completely torn away in places, and only two perfect and two imperfect sacs remain. 

 There is sufficient evidence to show that the genital sacs form very nearly a complete 

 ring. Two of the sacs are close enough to touch each other, and others show only a 

 very slight separation. 



Measurements. — (The specimen is rather flattened out.) Diameter of the central 

 disc, 23 mm. Diameter of the muscle-band, 35 mm. Diameter of the stomach, 

 16 mm. Length and width of pedalia, 3*5 mm. 



Atolla ivyvillei, Haeckel, 1880. 



Atolla wyvillei, Haeckel, 1880, p. 488; Haeckel, 1881, p. 113, pi. xxix. ; Vanhoffen, 1902, p. 13, 

 Taf. v. fig. 22. 



Station 413, lat. 72° 02' S., long. 23° 40' W. Vertical net, 0-1000 fathoms. 

 15th March 1904. 



At this station was taken an Atolla which is in very bad condition. Its stomach 

 and gonads are completely gone, and the umbrella is flattened out. 



The periphery of the central disc is distinctly divided into large lobes, and the 

 radial furrows separating the lobes are rather broad. The furrows resemble those in 

 Vanhoffen's figure of Atolla ivyvillei much more than those in the one he gives of 

 A. ver villi. It is upon the shape of the furrows that I have decided to call the 

 specimen A. wyvillei rather than A. verrilli. There are twenty-two tentacles, and 

 the marginal lobes are without warts. The pedalia have a slight longitudinal 

 furrow. As the diameter of the muscle-band is only 25 mm., the specimen is about 

 half-grown. 



Atolla ivyvillei was first found by the Challenger expedition at the depth of about 

 2000 fathoms. Three specimens were taken about midway between the Kerguelen 

 Islands and Melbourne (lat. 53° S., long. 108° E.), and two specimens in the South 

 Atlantic Ocean off the coast of Patagonia (lat. 42° S., long. 56° W.). The Valdivia 

 expedition secured a specimen south-east of Bouvet Island (lat. 56° S., long. 14° E.) 

 in a vertical net down to 1500 metres (821 fathoms), and another specimen 

 off Kemp Land (lat. 63° S., long. 57° E.) in a dredge down to 4600 metres 

 (2517 fathoms). 



TRANS. ROY. SOC. EDIN. VOL. XLVI. PART II. (NO. 10). 36 



