SYSTEMATIC AND BIOLOGICAL ACCOUNT 43 



In the South Atlantic it was taken by ' William Scoresby ' at several stations on the Patagonian Shelf 

 between Magellan Straits and the Falkland Islands at temperatures of from 5 to 6° or 7 C. 



On the eastern side of the South Atlantic 'Discovery' found the species at Station 104, about 

 seven degrees south of the Cape, and south of the sub-tropical convergence in lat. 41 33' 30" S. and 

 long, if 58' W. 



Bigelow gave its known temperature range as between 7-2° and 211 C. Kramp (1942) gave records 

 from South-west Greenland at temperatures between about 3 and 47 C. ' Mabahiss ' took a small 

 specimen at the surface, temperature 26-6° C, salinity 35-82 % at Station 39, about 80 miles north-west 

 of Sokotra on 25 November 1933. The fact that Physophora hydrostatica was at the surface at such 

 a high temperature is in itself of interest. No specimen has ever been recorded from this part of the 

 Indian Ocean before. The only other Indian Ocean records are those of Haeckel (Discolabe quadrigata), 

 but there may be some doubt whether all his Ceylon specimens belonged to this species (Garstang, 

 1946). The so-called record by Quoy & Gaimard (1833) of Physophora australis is based on figures 

 which do not for certain, in my opinion, represent Physophora. 



The ' Mabahiss ' specimen is small, about 15 mm. overall, and has five attached buds of nectophores 

 and six detached, crushed and deformed ones. All the palpons are missing, but one half-grown 

 gastrozooid with a half-grown tentacle is attached, as are three younger ones, each with only a rudiment 

 of a tentacle. Some of the tentilla on the former are unmistakably characteristic of similar stages in 

 Physophora. The nectophores and the course of their radial canals have been compared and correspond 

 with those of good Mediterranean specimens. The nectophore was well figured in Bigelow & Sears's 

 'Thor' Report (fig. 49 — a little masterpiece). 



The 'Mabahiss ' specimen is somewhat younger than that figured by Haeckel (18886; pi. xx, fig. 13). 

 Like it, the small discoidal siphosome exhibits a one-sided dextral proliferation of buds. There are one 

 or two small buds proximal to the youngest gastrozooids which may be young gonophores. Though the 

 specimen is poor, incomplete and difficult to study, I have not the slightest doubt about its identity. 



A great deal more work is needed on the development and structure of this species. On 18 and 

 19 June 195 1, 'Scotia' took three young specimens to the north-west of the British Isles in the region 

 of 19 N., 12 W. It was these that first made me doubt whether there is such a regular, dextral 

 sequence of cormidia arranged in vertical, trimorphic series as maintained by Garstang (1946). 

 My own tentative view is that the peripheral margin of the disc to which the cormidia are attached 

 does indeed correspond with the ventral median line of a twisted macrostele stem. This does not mean 

 that that is its phylogenetic history. I made a large collection of larvae of the species at Villefranche, 

 and studied alive, anaesthetized, and preserved two full-grown specimens. There is no time to complete 

 the morphological study of the material now in the British Museum collection before submitting this 

 report, but a cursory examination of the ' Scotia ' specimens shows that the lower one of the two rows 

 of palpons on the nascent lobe is a secondary one, and has not been caused by deformation, through 

 squeezing, of a single row, as suggested by Garstang. It also suggests that the upper row itself is not 

 a single sequence. This view is borne out by a study of the series of larvae. Garstang could not 

 understand how the spiral winding of a uniserial trimorphic stem could, in theory, produce the 

 parallel coronas ' as we see them ' in Physophora, but I think that Claus's (i860, 1878) interpretation of 

 homology is quite correct, though the Physophora condition is probably primitive and the macrostele 

 is derivative. 



Let us start with Text-fig. 10 [1], the generalized, uniserial, macrostele arrangement: theoretically 

 this could give rise to, or be derived from [2] and [3]. In Physophora, omitting secondary palpons, 

 we find the arrangement [4] . If the budding area is not studied closely we can easily get the impression, 

 which Garstang seems to give, of an arrangement such as [5]. 



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