OPHIURANS OF UNITED STATES NATIONAL MUSEUM. 19 



The specimens gathered by the Albatross at station 2573 are all very large, the 

 diameter of the disks varying from 20 to 27 mm. None of them is perfectly well 

 preserved and most of the arms are broken more or less close to their bases. I obser\'e 

 in every one of them a radial comb formed by small rectangular papillse which become 

 smaller as they pass over to the under side; Verrill seems to consider this comb as 

 only occasional. 



I am ghid to have been able to study these examples and to compare their charac- 

 ters with those of the other very closely allied forms which were described under 

 the various names mentioned. It was H. L. Clark who, in his most interesting 

 paper on the Ophiurans from the Northern Pacific (11, p. 62), suggested that 0. 

 irrorata Lyman, orbiculata Lyman, grandis Verrill, involuta Koehler, and tumulosa 

 Liitken and Mortensen, ought to be united in one species to which the name of 

 0. irrorata should be applied. The clever American naturaEst upheld his opinion 

 by very convincmg arguments which have completely satisfied me, the more so as 

 I myself had already had an opportimity to point out the close affinities existing 

 between 0. orbiculata, irrorata, and involuta, when I studied the Ophiurans from 

 the Investigator (97, pp. 295 and 302). Moreover, I suggest the idea of adduig to 

 the synonyms indicated by Clark, O. mundata, a species introduced by mo m 1907 

 for an Ophioghjplia which I had referred at firet to 0. irrorata, as I mentioned 

 recently (09, p. 153). As a basis of distinction between this former species and 

 0. irrorata, I had first noted the thickness of the disk, the shape of the mouth 

 shields, and the absence of spines, indicated by Lyman on the upper face of the 

 disk in the latter; these differences are of no more importance than those referred 

 to in order to separate from 0. irrorata the various species mentioned above by 

 H. L. Clark. Moreover, 0. mundata diffei-s but slightly from 0. grandis Verrill, and 

 certainly, had this writer given a drawing of tlie latter, I should without any hesi- 

 tation have referred to this species the specimens from the Travailleur and the Talis- 

 man as well as those from the Princesse Alice which I denominated 0. mundata; 

 but one knows how difficult it is to identify the species described by Verrill. Liitken 

 and Mortensen also related their 0. tumulosa to 0. grandis and pointed out that, 

 the latter not havuig been figured, it became very difficult to establish the connec- 

 tion between the two species. 



If thus understood, 0. irrorata has a very wide geographical distribution, which 

 might be compared with that of OfMmnusium lymani, as II. L. Clark points out, 

 but the former shows a much more conspicuous polymorphism than the latter. 

 There is no doubt that the differences which have been noticed do not proceed 

 exclusively from the sizes of specimens from the different knowTi localities; after 

 our Ophioghjpha has been found at a greater number of stations, it ^vill perhaps 

 be useful to keep, for variety's sake, some of the names imder which it is known 

 in zoological nomenclature. 



In one of the examples gathered by the Albatross, which I have illustrated 

 in plate 1, figs. 3 and 4, one of the araas has been broken near its base and includes 

 a restored part which offers certain peculiarities. As seen from the upper face 

 (fig. 4), this arm first shows three normal articles after which come the regenerated 

 articles, the first nine of which display anomalies as to the shape and arrangement 

 of the brachial plates which remind one of those described by me in Ophionotus 



