222 E. W. MACBEIDE. 



filled up will become evident when I state in the first place, 

 that my researches have made it clear that the Crinoids are 

 only very distantly related to the other classes of Echinoderms, 

 and secondly, that our previous knowledge of the metamorphosis 

 of Asterids and their allies was confined principally to the 

 changes which take place in their external form. 



It will be most convenient, I think, to give first a general 

 account of the development, and then to point out how far the 

 results of other workers have been confirmed, as by this means 

 needless repetition will be avoided. 



Methods adopted. 



My material consisted of a large number of larvse of all 

 stages including those which had just completed the metamor- 

 phosis, and of a considerable number of young adults varying 

 from an age of about three weeks to several months from the 

 metamorphosis. Of these the former, with the exception of two 

 small collections made by myself in Plymouth, 1893, and Jersey, 

 1894, were collected for me and preserved according to my 

 directions by the authorities of the Naples Zoological Station ; 

 the latter were obtained for me and preserved by myself during 

 my stay in the Naples Station in 1892. I have to express my 

 deep sense of my indebtedness to Prof. Dohrn for his kindness 

 in meeting my wishes, and to Cav. Salv. Lo Bianco for the 

 extreme care and attention with which he carried out my 

 directions. 



All the stages were preserved in osmic acid, followed by 

 14 — 24 hours in Miiller's fluid, as this method had yielded me 

 the best results in the case of Ophiurids. It makes the speci- 

 mens exceedingly brittle, but at the same time gives the most 

 excellent preservation of the minute histology; preserved in 

 this manner the various tissues are differentiated as to their 

 staining capacities, so that the sections look almost like coloured 

 diagrams. 



On account of their brittleness, and in order to avoid 

 shrinkage in the tissues, the larvge were embedded in celloidin, 

 and the celloidin block subsequently embedded in paraffin. 



