The Comatula-collection of the Leyden Museum is one of considerable importance, owing to its containing a large proportion of the types of the species described by Johannes Müller in his classical memoir ¹), »Ueber die Gattung Comatula Lam. und ihre Arten.” Müller’s descriptions, however, are notoriously incomplete, and have undergone no revision since their publication nearly forty jears ago, during which time a very large number of Comatulae have been discovered. Some of these have been referred with more or less success to one or other of Müller’s species, but without careful comparison with his types no accurate specific determinatious have been at all possible. When I visited the Leyden Museum last autumn for the purpose of examining the seven types of Müllerian species which it contains, I was not surprised to find a number of other Comatulae in the collection. Thanks to the good offices of my friend Dr. Hubrecht, to whom I am indebted for many acts of kindness, the whole of the foreign Comatula-collection numbering twentyfive specimens was sent over to my laboratory at Eton, in order that I might study it in more detail than was possible during a short visit to the Museum. For this act of liberality on the part of the Director, Dr. Schlegel, I would here express my heartiest thanks.