124 Scientific Proceedings, Royal Dublin Society. 



in doubting their existence, as Grosse has given no proof verifying 

 his assertions." Perhaps repeated reiteration may convince Pro- 

 fessor Hertwig. 



Though Grosse gives S. miniata, S. venusta, and S. nivea as 

 distinct species, nevertheless he twice (Actin. Brit., pp. 42 and 

 66) admits that they very closely approach one another. Besides 

 those points of similarity mentioned by him, the following may 

 be noticed: — (1). Orange-cored tentacles, which Grosse describes as 

 characteristic of S. miniata, may be present also in a specimen of 

 either of the other forms. I have found them in all the Irish 

 specimens of S. venusta and of S. nivea that I have seen. (2). The 

 same arrangement of the lines which mark the mesenteries on the 

 body- wall is to be found in all three forms, that is, the lines which 

 mark the mesenteries belonging to the outer row of tentacles are 

 continued but a short way down the column from the margin 

 not longer than these tentacles themselves, while those relating 

 to the mesenteries, corresponding to the other rows of tentacles, 

 may be traced throughout the entire length of the column. 



On the whole, however, Grosse is, I think, right in keeping 

 the three species distinct. There is less difficulty in keeping 

 Sagartia miniata separate from the other two than in keeping 

 them separate from each other. A Sagartia miniata has larger 

 tentacles, and those but half as many as a S. venusta, or a S. nivea 

 of equal size. Its disk is more undulated and generally more 

 overhanging than that of either of the others ; so that it comes 

 nearer Sagartia bellis, in its form, than they do : it resembles 

 rule, may readily be seen to be arranged twelve in the first and 

 S. bellis, too, in the arrangement of its tentacles, which, as a 

 second rows, twenty-four in the third, forty-eight in the fourth, 

 and so on. 



In distinguishing S. nivea from S. venusta the most salient point 

 of difference is undoubtedly to be found in the colours of their 

 respective disks. On this point I can fully confirm what Grosse 

 says (Actin. Brit., p. 6Q) as to the constancy of the colouring in 

 S. venusta. This constancy is the more remarkable, as while 

 specimens of S. nivea exhibit on their disks every shade from snow- 

 white to greyish-olive (which constitute the distinguishing colours 

 of Crosse's two varieties, immaculata and obscurata), yet I have 

 never observed a specimen with anything even approaching to any 



