n8 DISCOVERY REPORTS 



St. 177: S. Shetlands, 1080 m. St. 187: Palmer Archipelago, 259-354 m. St. 190: Palmer Archi- 

 pelago, 93-126 m. St. 474: S. Georgia, 199 m. St. 1948: S. Shetlands, 490-610 m. 



External appearance (Text-fig. 45 A). This species is generally found in groups of several indi- 

 viduals growing together, attached basally to bottom material, and to each other by irregular areas of 

 their sides. In some cases there is little or no encrusting matter on the test, but in others the whole 

 body except the siphons is covered with sand, small stones and broken shell. The shape is variable, 

 often upright and sometimes rather squat, and the siphons may be short or remarkably long (Text- 

 fig- 45 A). 



Text-fig. 45. Pyura discoveryi (Herdman) (St. 474) : A, specimen with long siphons ; B, the same with test removed ; C, dorsal 

 tubercle; D, oral tentacle; E, hepatic tubules; F, showing position of left gonad (St. 1948); G, right gonad of same specimen. 



Siphons. According to Kott (1954) there are no spines in the lining of the siphons, and I also can 

 find none. 



Tentacles. The tentacles number sixteen to twenty and are only slightly branched (Text-fig. 45 D). 



Dorsal tubercle. The opening of the dorsal tubercle is basically U-shaped with the ends of the 

 limbs variously bent ; usually both are turned outwards, or the left one outwards and the right one 

 inwards, or one or other may point forward (Text-fig. 45 C). 



Branchial sac. Some authors have said that there are six branchial folds on each side (Herdman, 

 1910; Hartmeyer, 191 1; Kott, 1954) and others that there are seven (Sluiter, 1914; Arnback, 1938; 

 van Name, 1945). In all the specimens from the 'Discovery' collection that I have examined there 

 are seven folds, and although the ventral fold is lower than the others, it is unmistakably present. 

 This finding agrees with Arnback's careful review of the question (see Arnback, 1938, pp. 30-2). In 





