6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



The color in alcohol is white, the aboral side of the disk some- 

 times faintly tinged with green ; the disk shows a brownish yellow 

 patch at the base of each arm, and more or less coarse irregular 

 mottlings of the same color ; the arms are frequently and narrowly 

 banded with brownish yellow, the bands occupying usually about 2 

 upper arm plates and being separated by usually 1 or 2 upper arm 

 plates. 



With these specimens of Ophiocomella parva were five specimens 

 of Ophiact is savig 1 1 y i . 



Remarks. — Dr. Hubert Lyman Clark, to whom I sent one of these 

 specimens of Opliiocomella parva for examination, writes that he is 

 confident it is nothing but a young specimen of Ophiocoma alexandri. 

 There is no evidence that Ophiocoma alexandri occurs at Clipperton 

 Island and, indeed, such occurrence is quite unlikely, for O. alexandri 

 has never been found in any locality inhabited by 0. scolopendrina. 



The National Museum possesses a young specimen of Ophiocoma 

 alexandri with the disk about 2.3 mm. in diameter and the arms about 

 9 mm. long, and another with the disk 3.6 mm. in diameter and the 

 arms about 15 mm. long, both collected by John Xantus at Cape San 

 Lucas, Lower California (U.S.N.M. 1 171 ) . Both of these, which are 

 considerably smaller than the largest specimens of Ophiocomella 

 parva, have 5 arms, and they differ markedly from the specimens 

 identified as that species. 



In young Ophiocoma alexandri the granules on the disk are much 

 coarser than they are in Ophiocomella parva, and are shorter with 

 more swollen sides and more broadly rounded tips. Very small radial 

 shields are visible, more or less concealed by one or more granules. 



In young Ophiocoma alexandri the upper arm plates are more 

 fan-shaped than in Ophiocomella parva — that is, they have straighter 

 proximally convergent sides. 



In Ophiocoma alexandri the arm spines are longer than in Ophioco- 

 mella parva, especially beyond the bases of the arms, and less rapidly 

 tapering, and those on the proximal arm combs are less strongly 

 flattened. The combs just beyond the disk in young Ophiocoma alex- 

 andri have usually 5 spines, those following 4, and those in the outer 

 portion of the arms 3. In Ophiocomella parva the combs never have 

 more than 4 arm spines. 



The first two tentacle pores in young Ophiocoma alexandri have 

 each 2 tentacle scales ; in Opliiocomella parva the second and following 

 pores have a single tentacle scale, and the first has usually a single 

 scale, though sometimes 2. 



