NEW FORMS 125 



a prebrachial stage, the oldest with three whorls of cirri, which I believe to be of the 

 new species Isometra hordea. There are twenty, the youngest with the beginnings of 

 arms, the oldest with only two whorls of cirri, which are of Notocrinus virilis. The fully- 

 formed larva of this species has been described by Mortensen (1920). 



NEW FORMS 



The proportion of new forms is very large : I have described ten new species and one 

 new variety. One of the new species, Notocrinus mortenseni, belongs to the peculiar 

 genus for which Mortensen found it necessary to establish a new family, the Noto- 

 crinidae (Mortensen, 1918); only the type species, A^. virilis, also from the Antarctic 

 and abundantly represented in the present collection, was previously known. Clark 

 (1937) has recently described a new species of Florometra, F. mawsoni, from the Ant- 

 arctic. It was taken by the Discovery vessels and they also found three specimens of a 

 new species, F. antarctica. 



There are three new species of Isometra. Two resemble /. vivipara but differ too 

 strongly from it to be described as identical ; the third, /. hordea, is undoubtedly a 

 distinct form. 



The other five new species are of smaller forms, each represented by a few specimens 

 only. For one of them, unique among Antarctic comatulids in that it lacks oral pinnules, 

 I have had to create a new genus, Kempometra. Three appear to be new species of 

 Eiimorphometra of which two species, one from the Antarctic and one from Marion 

 Island, were previously known. I have described a new species and a new variety of 

 Phrixometra, a genus previously known from one species taken off the River Plate. 



CARE OF THE BROOD 



The main interest of the collection is that it contains so many species which care for 

 the brood ; which are, in other words, viviparous. 



The vast majority of comatulids shed their eggs directly into the sea. Only three 

 viviparous species were previously known. In this paper I add to that number five new 

 species and one new variety from the Antarctic, and two described species, one from the 

 Antarctic and one from off the River Plate, which their authors had not recognized as 

 viviparous. Thus there are now eleven known viviparous comatulids. 



The three previously known species were Isometra vivipara from the Patagonian 

 shelf, the Burdwood Bank and the Antarctic; Phrixometra nutrix from the Burdwood 

 Bank ; Notocrinus virilis from the Antarctic. All three were taken by the Swedish South- 

 Polar Expedition and they and their viviparous habits were described by Mortensen 

 (1918, 1920).^ 



1 The care of the brood in Isometra vivipara had been described long before by K. A. Andersson (1904), 

 who did not however recognize the species as new but regarded it as Jlntedon hirsuta { = Eiimorptiomcfra 

 hirsuta). 



