94 



DISCOVERY REPORTS 



Genus Caenagnesia Arnback, 1938 

 Caenagnesia bocki Arnback (Text-fig. 31) 



Caenagnesia bocki Arnback, 1938, p. 41, pi. 2, figs. 20-22. 

 Agnesia complicata Kott, 1954, p. 151, figs. 32, 33. 

 Occurrence. St. 42: S. Georgia, 120-204 m. St. 181: Palmer Archipelago, 160-335 m - St. 182: 

 Palmer Archipelago, 278-500 m. 



External appearance. The shape of these specimens is very much as described by Arnback (1938). 

 In some of them there is a coating of fine sand or mud on most of the test. One specimen (St. 182) 

 has fine test processes arising from the lower part of the body, as in the type specimen. The largest 

 specimen is only 15 mm. in length, as compared with 20 mm. in Arnback's material, and 30 mm. in 

 Kott's material. 



4.0 mm 



Text-fig. 31. Caenagnesia bocki Arnback (St. 42): A, specimen with test removed; B, dorsal tubercle. 



Internal structure. The 'Discovery' specimens show remarkable agreement with Arnback's 

 detailed account. The numerous oral tentacles are arranged in five distinct circles. The rectum appears 

 to be a little shorter than that shown in Arnback's fig. 20. 



Remarks. This species has been recorded only twice before; off Graham Land (Arnback, 1938), 

 and off Enderby Land (Kott, 1954) if we accept Agnesia complicata Kott as a synonym of C. bocki. 

 Kott's description of the specimens which she examined from near Enderby Land agrees very closely 

 with Arnback's description of the type specimens, except in having a better developed branchial sac. 

 In A. complicata there were twenty-four transverse rows of infundibula each with seventeen infundi- 

 bula, as compared with twelve rows each with thirteen or fourteen infundibula in C. bocki. This 

 difference can be accounted for by the larger size of the specimens from Enderby Land. 



Kott mentioned ' bifid languets ' alternating with each transverse row of infundibula and not with 

 each two rows (cf. A. septentrionalis Huntsman, A. glaciata Michaelsen, van Name, 1945, p. 201). 

 These ' bifid languets ' are in fact the bifid papillae which are present on the transverse vessels. True 

 languets, to which Huntsman referred in A. septentrionalis, are present only along the roof of the 

 branchial sac. Caenagnesia, having a continuous dorsal lamina, has no languets. 



Distribution. Antarctic (Graham Land, South Georgia, Enderby Land). 



