PART 5 



A MONOGRAPH OF THE EXISTING CRINOID3 



635 



TABLE 16. Measurements of specimens of Isometra vivipara in the British Museum, the Stockholm 



Museum, and the Copenhagen Museum. 



Jensenius Madsen of the Copenhagen Museum, I have also been able to study a syntype 

 definitely from station 5, within the Antarctic, which, like the rest, has P 5 usually the 

 first genital pinnule and PI larger than P 2 . 



Another antarctic record is that from Discovery Investigations station 175 in the 

 Bransfield Strait which Dr. Dilwyn John included in Isometra vivipara although it shows 

 some differences from the subantarctic material taken by the same source. 



The specimen is a female and on all the arms P a is the first genital pinnule, though 

 it may be only slightly swollen. In all the other known specimens of vivipara the 

 first genital pinnule is at P 5 or beyond, rarely P 4 . Also Dr. John noted that the ex- 

 tension of the segments of the genital pinnules is not so great as in the subantarctic 

 specimens. The brood pouches contain many fewer eggs and embryos, two examined 

 by Dr. John each having only three embryos and one egg. The position of the second 

 syzygy is abnormal, on eight of the arms it is between brachials 11 and 12, on one 



E56-622 67 42 



