228 DISCOVERY REPORTS 



three latter differ in the absence of subanal tube feet (besides other characters). As for 

 A. bidevs (which as stated above, p. 226, is perhaps better regarded as a separate species 

 than as a variety of A. cavernosiis) it differs markedly in the form of the pedicellariae, as 

 seen from the figures given here for comparison (Plate IX, figs. 9-1 1). 



Abatus Philippii, Loven 



Abatus Philippii, Loven, 1871. Om Eclmioideernas hyggnad. Ofvers. Vet. Akad. Forh., viii, p. 6. 



A. Philippii, Mortensen, 1910. Swedish South Polar Exped. Echinoidea, p. 83, pis. xi, figs. 6, 

 9-13 ; xix, fig. 47. 



A. Philippii, H. L. Clark, 1917. Hawaiian Echini. Echinoneidae . . . Spatangidae, p. 175. 



For other literary references see my work on the Echinoidea of the Swedish South Polar 

 Expedition, loc. cit. 

 St. 181. 12. iii. 27. Schollaert Channel, Palmer Archipelago, 160-335 m. i specimen and frag- 

 ment (dorsal side) of another. Both are males; still, I do not think the identification as A. Philippii 

 doubtful. 



The validity of A. Philippii as a distinct species is somewhat uncertain. Clark {op. 

 cit., 1917) suggests that it may be based only on specimens of ^. cavernosiis in which the 

 posterior petals have not yet been transformed into marsupia. The material at my 

 disposal does not support Clark's suggestion that the marsupia of the female do 

 not develop contemporaneously, but that the anterior ones develop first and the 

 posterior ones later. Thus in a couple of specimens of 30-32 mm. length I find all the 

 marsupia equally developed, though not very deep as yet, the specimens being not yet 

 mature, as is evident from an examination of the gonads. On the other hand, the fact 

 that A. Philippii appears to be on the whole of rare occurrence tends to support Clark's 

 suggestion. It may also be possible that the forms with only the anterior petals trans- 

 formed into marsupia may represent aberrant specimens of cavernosiis. However this 

 may be, I think it desirable for the present to designate these specimens with only the 

 anterior petals transformed into marsupia under the name A. Philippii, whether it be 

 a "forma", an "aberratio", a variety, or a true species. 



Abatus Agassizii (Pfeffer) 

 Abatus Agassizii, Mortensen, 1910. Swedish South Polar Exped. Echinoidea, p. 86, pis. x, 



figs. I, 3. 5> 9. H; xix, fig. 4- . o -J 



A. Agassizii, H. L. Clark, 1917. Hawaiian Echini. Echinoneidae. . .Spatangidae, p. 176. 

 ? A. 'Agassizii, H. L. Clark, 1925. Cat. Recent Sea-Urchins Brit Mus., p. 204. 



St. 55. 16. V. 26. Entrance to Port Stanley, East Falkland Islands, 10-16 m. i young specimen. 



St. 388. 16. iv. 30. 56° 19' S, 67° 10' W, 121 m. I specimen. 



St. WS 25. 17. xii. 26. Undine Harbour, South Georgia, 18-27 m. 2 young specimens. 



22. X. 34. Weir Creek, Falkland Islands, 3-5 m. 3 young specimens. 



Although these specimens are quite young, 5-18 mm. long, I have no doubt that the 

 identification is correct. The absence or feeble development of the subanal tube feet 

 affords a marked difference, particularly from A. cavernosiis, in which these tube feet are 

 already well developed in specimens which have just left the marsupium. As for the 



