474 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



to develop. Luidia ciliaris is not a common species in 

 the neighbourhood of Port Erin; and, so far as my 

 knowledge of its distribution goes, is confined to the 

 deeper waters. So far as the experience of Gravely and 

 myself goes, the occurrence in the plankton of Port Erin 

 Bay of brachiolariae undergoing metamorphosis is rare. 

 Gravely 's collection contains three, evidently of one 

 species, taken in August (fig. 13, PI. II), and my own 

 collection but one, taken in June. Mortensen informs 

 me that on certain parts of the coast of Denmark meta- 

 morphosing brachiolariae of Asterias rubens may be seen 

 swimming at, or near, the surface of the sea in large 

 numbers during July; and one of the American species 

 is represented by similar numbers in the waters of Wood's 

 Hole. Their rarity in Port Erin Bay and its neighbour- 

 hood cannot, therefore, be explained by the assumption 

 that when passing through their later stages these larvae 

 seek the deeper waters. 



Figs. 14 to 18, PI. II, represent stages in the 

 development of the larva of Solaster, but whether of 

 S. papposus or of S. endeca I cannot say with certainty at 

 present. Both species occur in the immediate neighbour- 

 hood of Port Erin, but S. papposus is probably the more 

 abundant. Comparison of my figures with those of 

 Gemmill (3) will show that there is close agreement, at 

 least in external form, between the larvae from the plank- 

 ton of Port Erin and those of S. endeca reared in the 

 Biological Station at Millport. It is probable, however, 

 that both species are represented. The larva shown in 

 fig. 19 is very similar to that of which the external form 

 only is shown in fig. 18, Plate II, of GemmilPs paper. It 

 is probably not of the same species as that shown in 

 figs. 15 to 18, but the few details of its structure which I 

 have drawn show that the two are closely related. My 



