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BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



This offers a rather striking character differentiating the two forms, 

 so that it is tempting to regard the form with the bush-shaped hairs 

 as a separate species, the more so as there are also some other differ- 

 ences. For instance, the secondary spines are rather more slender, 

 especially the marginal ambulacral spines, and also more greenish 

 than in the typical form. The primaries are white, or faintly banded 

 with red, as in the typical form. The interporiferous area also is in 

 general broader and more densely covered with miliary tubercles 

 than in the type (pi. 75, fig. 4). Some of the specimens have the 

 upper areoles more or less effluent, recalling the condition generally 

 found in S. effluens. In fact, had I only these Albatross specimens at 

 my disposal I should hardly have hesitated to regard this form as a 

 separate species. However, the several specimens of both the typical 

 form and of the variety which I have myself collected in the Japanese, 

 Philippine, and Moluccan seas (at the Kei Islands) offer such an 

 intermingling of all characters that I find it quite impossible to give 

 any reliable characters other than the one pointed out above; that 



Fig. 20.— Hairs from the primary spines of Stylocidaris reini (Doderlein) (a), St. Reini, var 



CLADOTHRIX, NEW VARIETY (6), AND ST. ANNULOSA, NEW SPECIES(c). X115 



is, the difference in the shape of the hairs on the surface of the pri- 

 mary spines; but also in this character intermediate forms occur, 

 which it is difficult, or rather, impossible, to refer definitely to one 

 form or the other. Thus in spite of the conspicuous difference when 

 forms pronouncedly illustrative of the two types are compared, I 

 hold it unjustifiable to give the form with the bush-shaped hairs 

 more than varietal rank. 



It may be mentioned that generally speaking the typical form has 

 more slender primaries with somewhat less numerous serrate ridges 

 than the variety, which generally has the primaries somewhat swollen 

 at the base and the serrations more numerous, the serial arrangement 

 often being indistinct. But in the Albatross specimens of the variety 

 the serrations form distinct longitudinal series and the primaries are 

 in general slender, whereas in the specimen of the typical form from 

 station 5617, on the contrary, the primaries are swollen at the base 

 (pi. 66, fig. 2). It should also be especially pointed out that the num- 

 ber of miliary tubercles in the interporiferous zone of the ambulacra 



