30 KmVARl) T. HliOWXK. 



The ' Southern Cross ' collection contains three specimens, taken at Cape Adare. 

 The largest is in a mutilated condition, having a clean-cut hole through the centre 

 of the umbrella. The stomach and mouth have completely disappeared, and so also 

 have the proximal ends of the gonads, but the margin of the umbrella is in good 

 condition. The two other specimens are intermediate stages in bad condition. 



The ' Discovery ' collection also contains a mutilated specimen, which was taken 

 in McMurdo Sound on 27th March, 1903, through one of the holes in the ice. 



Description of the Adult. Umbrella slightly convex, and thick, about four times 

 as broad as high. Velum broad. Four radial canals with sinuous margins in the 

 gonadal regions, but without conspicuous lateral diverticula. Gonads large and broad, 

 arranged in lateral and transverse folds, and extending over nearly the whole length 

 of the radial canals. Tentacles long and slender, about 300, with a reddish pigment 

 in the endoderm, and with laterally compressed basal bulbs. One long club-shaped 

 cordylus between every two tentacles. 



Size. Umbrella up to 60 mm. in diameter. 



Notes on the Specimens. The ' Discovery ' specimen shows that the gouads extend 

 from the base of the stomach nearly to the circular canal. They are arranged in a 

 series of lateral folds, along both sides of the radial canals, and form a closed tube. 

 There is no evidence of a mouth extending over and along the gonads, a character 

 which distinguishes Staurophora from Ptychogena. The radial canals of Ptychogena 

 antarctica have not the conspicuous lateral diverticula of P. lactea. In the proximal 

 part of the canals there about two very short irregular diverticula, but the margins of 

 the canals are of a rather irregular wavy nature, so that the pinnate arrangement of 

 the gonads, conspicuous in P. lactea, is absent in this species. 



The tentacles are closely packed together round the margin of the umbrella, and 

 are like long, slender threads, some of which measure 40-50 mm. in length. The 

 endoderm of the tentacle, including the basal bulb, contains a dark reddish pigment 

 (in formalin). Sections show that the pigment is in minute globules, either isolated 

 or grouped in clusters. The ectoderm of the tentacle is thick, and composed of many 

 layers of very small cells, amongst which are numerous long slender nematocysts, 

 about 15 /j. in length. The nematocysts frequently congregate in clusters or layers 

 adjacent to the rnesoglsea, and look in that position just like spicules. The basal bulbs 

 of the tentacles arc laterally compressed (PI. II., fig. 8) and the upper (aboral) side of 

 the bulb is arched, but when viewed from the aboral side, the basal bulbs look long 

 and tapering (PI. II., fig. 7). 



The cordyli are long and club-shaped (fig. 9), and are situated on the margin of 

 the umbrella close to the velum. There is usually only one cordylus between every 

 two tentacles. The cordyli are without pigment. Some of the cordyli possess just a 

 few uematocysts similar to those in the tentacles. I have not noticed nematocysts in 

 a cordylus before, but here at any rate is an exception to the rule. Haeckel (1882) in 

 his description of Ptychogena pinnulata states that the cordyli appear chalk-white in 



