OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 275 



disk which are terminated in 0. ciliaris by a few short and un- 

 equal spinules instead of as in O. stelligera by a very regular crown 

 of spinules with the so characteristic stellate appearance (Kcehler 

 '04, p. 102). Only it is necessary here to show an important dif- 

 ference. It is especially in examining the dorsal surface of the 

 disk of O. stelligera as a whole, and without isolating the club 

 spines, under a lens or under a microscope that this stellate form 

 so characteristic of their heads, such as Doderlein has represented 

 and as is seen again in my photograph, is noticed; but as I have 

 explained above, when these club spines are isolated, and when in- 

 stead of being viewed directly from above, they are seen in profile, 

 the length and the thickness of each spinule may be judged ex- 

 actly, and it may then be seen that these are far from being per- 

 fectly identical. 



On isolating the club spines of the disk of the 0. ciliaris preserved 

 in the Paris Museum and examining them under the microscope, I 

 was struck with their perfect resemblance to the club spines of the 

 same size in my O. stelligera. If we compare the club spines of O. 

 stelligera shown in plate 102 as figures 2a and b with those of 0. 

 ciliaris (fig. 3) , we can not determine any important difference ; some- 

 times the spinules are fairly regularly arranged and almost equal, 

 sometimes they are unequal, as may also be the case in O. stelligera. 

 These spinules are sometimes shorter, sometimes longer, but these 

 variations have no importance and do not have to be considered. 

 Furthermore, I find these same variations in the different specimens 

 of O. ciliaris which I have examined, both in those of the Paris 

 Museum and in those of the Challenger expedition. Also we notice 

 that the club spines of O. ciliaris have the spinules shorter than is 

 usual in O. stelligera, but I find in different specimens of the latter 

 some club spines absolutely identical with those seen in O. ciliaris. 



It is impossible to find in the characters of the club spines of the 

 dorsal surface of the disk any important differences permitting the 

 separation of O. stelligera from the type specimens of O. ciliaris pre- 

 served in the Paris Museum. I believe, therefore, that they must 

 belong to the same species. 



I am convinced that when Lyman established O. stelligera he for- 

 got to compare it with O. ciliaris, for if he had then referred to the 

 characters of this latter species he would certainly have been struck 

 with the resemblances which they present. He would have been able 

 at least to indicate these resemblances and to explain why he thought 

 it necessary to create by the side of O. ciliaris the new species which 

 he called stelligera, while he was content to compare the latter with 

 O. carinata and O. pusilla. And Lyman knew O. ciliaris well, be- 

 cause he speaks of the original specimens which he had studied at the 



