UMBELLULIDAE 



267 



Station Depth {tn. 



1644 645 



16 January 1936 

 Ross Sea 



1645 



17 January 1936 



Ross Sea 



1652 



23 January 1936 



Ross Sea 



1948 

 4 January 1937 

 S. Shetland Is. 



Remarks on the specimens 

 I specimen, total length 15-5 cm. 



The cluster has 5 large autozooids and 4 equal buds, the positions of which are 

 evident from text-fig. 3, 6. The arrangement is obviously bilateral, but the displacement 

 of the primary polyp by the budding of the two dorsal autozooids indicates the develop- 

 ment of a bowl-shaped rachis. Siphonozooids are crowded in all interspaces between the 

 autozooids as well as on the tapering basal part of rachis below the cluster, many with 

 tentacles extended. 



435 I specimen, total length 55 cm. 



The lower part of rachis is bowl-shaped with 1 1 fully developed autozooids along the 

 brim. Inside the whorl one fully developed autozooid is seated near one side, and evi- 

 dently two buds are developing near the other side. The central field appears covered by 

 hairs because of the extended tentacles of the siphonozooids, which also give the part of 

 the rachis below the autozooid whorl a shaggy look. Between the autozooids of the whorl 

 no siphonozooids were visible. 



567 I specimen, total length 36 cm. 



Axis just above the holdfast i mm. thick,just below the cluster f mm. thick. Autozooids 

 with bodies up to 3 cm., tentacles up to 2-2 cm. long. One whorl consisting of 7 full-grown 

 autozooids and one small bud ; in the inner field one excentric, large autozooid. Siphono- 

 zooids all over the rachis, tentacles retracted. Typical magniflora. 



490-610 3 specimens. 



1, total length 36 cm. 

 The comparatively distinct holdfast is about 6-5 cm. long and rather fleshy like the 



stem. Axis just above the holdfast 2 mm. thick, just below rachis i mm. thick. It enters 

 the centre of the broad obconical basal part of rachis and disappears in the tissues. Auto- 

 zooids moderately contracted, body up to 2 cm., tentacles up to 1-7 cm. long. Five full- 

 grown individuals and one bud make up a basal whorl of autozooids. Within and above it 

 3-4 quite irregular crowded 'whorls' of autozooids are developed, and in all interspaces 

 between them and on rachis below the tassel, siphonozooids are thickly placed, some of 

 them with extended tentacles. Typical antarctica. 



2, total length 37 cm. 



Holdfast about 8-5 cm. long, with dimensions as in i. Holdfast and stem fleshy. 

 Autozooids moderately contracted, body length up to 2-5 cm., tentacles to 2 cm. There is 

 a basal whorl of 11 autozooids, and 4-5 quite indistinct and irregular 'whorls' on a short 

 spigot within the basal whorl. Here as in i the autozooids of the inner 'whorls' are a 

 little smaller than those of the base. Siphonozooids, often with extended tentacles, are 

 crowded between the autozooids and all over the rachis. Here as in the following 3 the 

 basal part is that of a typical magniflora, but the upper 'whorls' of the tassel have changed 

 the specimen into a typical antarctica. 



3, total length 38-5 cm. 



Holdfast contracted, about 9 cm. long, axis dimensions agreeing with i and 2. Specimen 

 fleshy. The upper part of the stem just below the cluster is strongly curved owing to 

 contractions of the coenenchyma. The basal whorl of the tassel consists of 1 1 flaccid 

 autozooids with bodies up to 3 cm. and tentacles up to 2 cm. long. The distal part of the 

 tassel is packed with irregularly placed, somewhat smaller autozooids, and all interspaces 

 between them are crowded with siphonozooids, some of them with extended tentacles. 

 Between the autozooids several new buds are observed. 



The Discovery collections contain no less than 26 specimens of different sizes from antarctic waters 

 which furnish a good basis for a discussion of the problem (Table, pp. 264 to 267). 



The smallest specimens (St. 181) are only 7-5 cm. long and besides the primary polyp they have one 

 pair of fully developed secondary autozooids and below them a pair of autozooid buds (text-fig. 3, 4). 

 Thus they correspond to Broch's (1957) text-fig. 4, iii, and text-fig. 5, no. 5 {Umbellula car- 

 penteri), although the rachis does not jut out above the primary polyp and the buds are placed a little 

 below the first pair of secondary autozooids. This probably is the ' normal ' case. 



In a third specimen from St. 181 (text-fig. 3, 5) with a total length of 47 cm., a third pair of auto- 

 zooids has evidently been developed at the dorso-lateral sides of the primary polyp, or the rachis has 

 been thickened a little at the same time as a lower (more ventral) pair has pushed the upper pair more 



