454 DR. S. F. HARMER ON THE 



The sessile statoblasts have the following measurements : — • 

 Length, 432^t-448^, average 442/^; breadth, 320/a-368u, 

 average 336 ^t ; average ratio, L : B, 1'317 : 1. 



If Braem is right in separating P. emargiiiata and P. fruticosa, 

 the proportions of the sessile statoblasts would alone justify the 

 reference of the Torquay specimens to P. emarginata rather than 

 to P. fruticosa. I am confirmed in the belief that they belong to 

 the former species by the fact that the annulus covers nearly the 

 whole of the central capsule on one sui'face of the statoblast 

 (figs. 15-17), as shown by Allman (56, pi. vii. fig. 7) in one of his 

 figures, and by Braem (90, pi. i. fig. 12), who has called special 

 attention to the importance of the character in question. 



In Kraepelin's series of measurements of the forms regarded 

 by him as belonging to P. princeps (87, pp. 112, 113) the average 

 ratio of length to breadth is given as 1'8:1, But he admits a 

 considerable variation in this respect, the limits given being from 

 2'79 : 1 to 1'53 : 1. It will be seen that my own measurement of 

 1'543 : 1 falls within these extremes, although it is much nearer 

 Kraepelin's lower figure. The highest ratio of length to bi-eadth 

 measured by me is 1"666 : 1, and the lowest is 1"333 : 1. The latter 

 ratio would bring the statoblasts well within the limits given by 

 Kraepelin for his P. poli/morpha, which includes P. repens auctt. 

 It thus becomes necessary to consider whether the Torquay speci- 

 mens should be referred to P. repens instead of to P. emarginata. 



I have accordingly compared the Torquay statoblasts with the 

 variety of P . fimgosa described above and with what I regard as 

 a typical form of P. repens^ obtained at Cringleford,near Norwich. 

 It will be seen from the figures that the floating statoblasts of 

 the Torquay specimens (figs. 15-17) are distinctly longer, in pro- 

 portion to their breadth, than those of either P. rep)ens (fig. 21) 

 OY P. fungosa var. coralloides (fig. 22), and that the annulus 

 covers much more of the central capsule. It will be remarked, 

 moi-eover, that in the Torquay specimens the annulus extends 

 over the central capsule further on one side than on the other 

 side of the statoblast, in agreement with P. emarginata var. 

 muscosa (fig. 18, from a Hamburg specimen) ; while in the other 

 two forms the annulus is about equally developed on both sides. 

 The floating statoblasts of P. fungosa (fig. 22) are distinctly larger 

 than those of P. repens (fig. 21). I have not obtained sessile 

 statoblasts of P. repens for comparison. Kraepelin denies the 

 existence of this form of statoblast in the typical P. repens, but 

 Braem (90, p. 6) claims to have found them. In P. fungosa the 

 sessile statoblasts (figs. 23-25) are very large, and possess a rather 

 well-developed annulus ; while they are smaller, and with a more 

 vestigial annulus, in the specimens of P. emarginata var. mus- 

 cosa, both from Hamburg (fig. 20) and from Torquay (fig. 19). 



I fully admit that the floating statoblasts of the Torquay 

 specimens are short as compared with those of moi-e typical 

 specimens of P. emarginata ; but it appears to me that the result 



