A MONOGRAPH OF THE EXISTING CRINOIDS 161 



erates situated on the second brachial, but never a single arm regenerating from this 

 ossicle. 



In his description of the specimens identified as albopurpurea in Mortensen's 

 collection Dr. Gislen said that the young can be distinguished from specimens of 

 pulchella by the less numerous cirri and by the slender arms composed of long and very 

 juvenile segments. The IBr series are also extremely long, and PI and P 2 have an 

 equal number of segments. 



A specimen from Mortensen's station 14 Gislen referred to C. manca because of 

 its short and numerous cirrus segments, combined with the short cirri, and because of 

 the long intersyzygial interval, although the dorsal spines on the cirri are tolerably 

 small. Specimens from station 9, with their short-segmented and strongly rolled up 

 cirri arranged in a single row on the centrodorsal he said may be regarded as the young 

 of manca. He remarked that evidently the dorsal spines are not very reliable as specific 

 characters. 



To sum up, Dr. Gisle"n maintained the separation of disciformis and manca on the 

 basis of the longer cirrus segments of the former, adding that the arms of disciformis 

 seem to be fewer in proportion to their length, the distal intersyzygial interval is 

 much shorter, the habitus is more slender, and the distal pinnules are longer and 

 more slender. One specimen he formally recorded as manca, but elsewhere men- 

 tioned, with some doubt, as disciformis. The differences given by Gisle"n are all 

 within the range of individual variation, or the variation resulting from differing 

 degrees of maturity, or the variation resulting from the response to the immediate 

 environment. He differentiated pulchella from manca by the smaller and less dis- 

 coidal centrodorsal, the longer cirrus segments with only inconspicuous carinations, 

 the absence of IIIBr series, the short intersyzygial interval, and the smooth P 2 . These 

 differences are in the direction of disciformis on the one hand, and albopurpurea on the 

 other, and merely indicate a more or less stable varietal form corresponding to 

 disciformis though differing from it in the lesser development of dorsal processes on the 

 cirrus segments. A specimen identified by him as albopurpurea had cirri resembling 

 somewhat those of manca, raising some doubt in his mind as to whether these two 

 supposed species are really distinguishable. One specimen recorded as manca he said 

 had, in a somewhat similar form, the characteristic dorsal spine of albopurpurea. But 

 elsewhere he referred to this same specimen as disciformis. In another place he said 

 that evidently the dorsal spines are not very reliable as specific characters. The 

 differences he gives in the cirri and arms of albopurpurea and manca are merely indi- 

 vidual, or are differences in the relative degree of maturity of the individuals compared. 



Dr. Gisle"n's study of these forms leads one to the conclusion that while the 

 names manca, disciformis, albopurpurea, and pulchella may be found useful in desig- 

 nating more or less stable forms or varieties within a single specific type, they certainly 

 can not be regarded as covering distinct species. 



Localities. Golden Hind; Tokyo Bay, Japan;' 15-22 meters; Alan Owston, 

 October 22, 1899 [A. H. Clark, 1908] (23, U. S. N. M., 35290; 35346 [original No. 5586]; 

 35374 [original No. 5586]; 35393 [original No. 5586]; 35396 [original No. 5586]). 



Oolden Hind.; Tokyo Bay; 24 meters; Alan Owston, October 22, 1899 (2, M. C. Z., 

 274). 



