POLYZOA OF WATERWORKS. 



453 



length to breadth, 2'497 : 1 *), while the annulus does not cover 

 so much of the central capsule as in the other species. In 

 F. emarginaia, on the other hand, the floating statoblasts are 

 less than twice as long as broad (average ratio : length to breadth, 

 1*868 : 1), while the annulus covers nearly the whole of the 

 " upper" side, leaving only a small portion of the centi'al capsule 

 uncovered. (3) In P. fruticosa the sessile statoblasts have a broad 

 vestigial annulus, and ai'e more than twice as long as broad (ratio, 

 2 "461 : 1), while those of F. emarginaia resemble the sessile stato- 

 blasts of P. repens, and have no annulus, while they are less than 

 twice as long as broad (ratio, 1-312 : 1). 



Through the courtesy of the authorities of the Hamburg 

 Museum, I have had the opportunity of examining specimens of 

 both var. viuscosa Kraepelin and var. sjjongiosa Kraepelin, from, 

 the original material described by that author. I have figured 

 a floating statoblast (fig. 18) and a sessile statoblast (fig. 20) of 

 var. muscosa, from the Hamburg material, for comparison with 

 the Torquay specimens. The measurements which I have made 

 of the statoblasts from Hamburg agree closely with those given 

 by Kraepelin, and are as follows : — 



Very few floating statoblasts are present in the sjjongiosa- 

 mateiial, in which there are a number of sexually produced 

 embryos. 



If Braem's criticism of Kraepelin's results is correct, it 

 follows from these measurements that both varieties, muscosa 

 and s23ongiosa, are to be regarded as forms of P. emarginaia ; 

 and in this I am following what I understand to be Braem's 

 opinion. 



The specimens sent from the Torquay Waterworks by Mr. S. 

 0. Chapnian appear to me to be referable to P. emarginaia, 

 as understood by Braem, although their floating statoblasts are 

 less elongated than in the Hamburg specimens. I find that these 

 statoblasts vary in length from 328^ to 416^ and in breadth 

 from 224^ to 264/x,, the average measurements (11 cases) 

 being-.— Length, 371 /i ; breadth, 240^; ratio, L : B, 1-543:1. 



* The ratio is calculated from the measurements given hy Braem. 



~ 31* 



