2o8 DISCOVERY REPORTS 



Mention may here be made of the curious fact discovered in Ophiomitrella falklai^dica 

 that the older young ones within the bursae may feed upon their younger brothers and 

 sisters. This recalls what was found in the viviparous Comatulid Isometra vivipara, 

 Mortensen, where the young Pentacrinoids, attached to the cirri of the mother, catch 

 and devour their brother and sister larvae on their passage from the marsupium in the 

 pinnulae, where they are hatched, to the cirri, where they are to attach themselves (cf. 

 my Report on the Crinoidea of the Swedish South Polar Expedition, 1918, p. 15). 



One cannot help wondering how the young ones, which in several species reach a very 

 considerable size within the mother, can get out through the genital slits, as for instance 

 in Ophiolebella biscutifera, where the young reach the size of 2 mm. in diameter of disk 

 and the genital slits are only 0-5 mm. long. It is astonishing how these young specimens, 

 in spite of their rigid and apparently inflexible skeletons, can assume the most irregular 

 shapes without even the most delicate of their plates being crushed when pressed 

 together in the bursae, and still assume a normal radiate form when they are born. 

 One must marvel also how the mother specimen can get food absorbed, when its stomach 

 is squeezed by the large young ones, or even reduced to a network among the young 

 ones, as in Ophiochondnis stelliger (cf. p. 260). 



A good many of the Antarctic Ophiurans were found to be infested with parasites, 

 mainly Crustaceans. The ectoparasitic Copepod Cancerillopsis was found on several 

 specimens of Ophiocantha disjuncta. The curious entoparasitic Copepod Ophioika (or 

 something related to it) was found in Ophiacantha vivipara, O. disjuncta, Ophiomitrella 

 falklandica, Ophiiira meridional is, and Ophiiirolepis partita. The Cirripedian Ascothorax 

 was found in Amphiura Belgicae and A. microplax. In A. Belgicae likewise a curious 

 sac-shaped, shell-less Gastropod was found, containing a number of embryos with shells 

 (Fig. 19, p. 282). In A. microplax disjuncta a Nematode was found coiled up in the male 

 gonads, and in Ophiochondnis stelliger a parasitic organism, probably referable to the 

 peculiar problematic Nidrosia, which I described from the gonads of Ophiiira Sarsi 

 (Ingolf Ophiuroids, p. 74). Finally I may mention that I found some specimens of 

 Ophiacantha rosea in the British Museum infested with Myzostoma, mainly at and 

 within the bursae. 



Several of the Ophiurids were taken in considerable numbers by the expedition and 

 must play an important part in the ecology of the Antarctic and sub-Antarctic seas ; but by 

 far the most numerous of them is Ophiocten amitinum, young specimens of which were 

 taken in several places off the Falkland Islands in incredible numbers, by hundreds of 

 thousands, if not by millions ! That they must form an important source of food for 

 other animals is evident, as also that they must be competitors for food, being in both 

 ways a factor of no small importance in the economy of these seas. 



