408 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



the cirri are short or of moderate length, with less than 40 segments; and the dorsal 

 surface of the division series is smooth, without ornamentation. 



Geographical range. From the Macclesfield Bank and the Philippine Islands to 

 the Pelew, Caroline, and Marshall Islands, Samoa, Fiji, the Tonga Islands, New 

 Caledonia, Torres Strait, and the Lesser Sunda Islands westward to the Red Sea and 

 Madagascar. 



Bathymetrical range. From the low-tide mark down to 245 meters. The species 

 of Stephanometra are especially characteristic of the zone from the low-tide mark 

 down to about 50 meters. Of the seven species, all have been taken in shore collecting, 

 five are not known with certainty from a depth greater than 51 meters, one is recorded 

 from 62 (possibly 73) meters, and one is recorded from 245 meters; there is some doubt 

 about the correctness of the last record. 



Remarks. The genus Stephanometra includes seven species, which are rather 

 sharply divisible into two groups. 



In the species belonging to the first group the outer cirrus segments bear long, 

 prominent, and sharp dorsal spines. These two species, S. echinus and S. tenuipinna, 

 are alike in all features except such as might well be attributed to the relative maturity 

 of the individuals assigned to one or the other. Although it is by no means certain 

 that S. tenuipinna is simply the young of S. echinus, this will very likely turn out to 

 be the case. 



In the five species belonging to the second group the distal cirrus segments are 

 wholly without dorsal spines, being at the most only slightly carinate dorsally. In this 

 group the species are differentiated by the characters presented by the proximal 

 pinnules. In all of them P 2 is enlarged, much stiffened, and spinelike. In one species, 

 S. spinipinna, P! is stiffened and spinelike, though considerably slenderer and shorter 

 than P 2 , being intermediate in character between the stout, much stiffened, and 

 spinelike PI found in S. echinus and S. tenuipinna and the slender and flexible PI 

 found in S. oxyacantha, S. spicata, S. protectus, and S. indica. When the characteristic 

 P! of S. spinipinna is typically developed the species is an easy one to recognize, but 

 hi this species PI is rather variable, and there is a suggestion of possible intergradation 

 between S. spinipinna on the one hand and S. spicata and S. oxyacantha on the other. 

 The four species in which P! is slender, delicate, and flexible are S. oxyacantha, S. spica- 

 ta, S. protectus, and S. indica. In S. oxyacantha the second-fifth or second-fourth 

 pinnules are stiffened and spinelike, in S. spicata the second and third, and in 

 S. protectus and S. indica only the second. But there is really no hard and fast 

 line of division between these forms. Pinnules of an intermediate type more or less 

 enlarged and much stiffened for a greater or lesser distance from their base, but with 

 the distal portion delicate and flexible, sometimes occur. As a result of the occurrence 

 of such pinnules some individuals are intermediate between S. oxyacantha and S. 

 spicata, while others are intermediate between S. spicata and S. protectus. Although 

 8. protectus and S. indica when typically developed appear very different, some 

 individuals from Ceylon have P 2 of a type intermediate between that characteristic 

 of S. protectus and that characteristic of S. indica. 



The species of the first group are somewhat limited in their distribution, occurring 

 from the Philippines to New Britain, the Paternoster Islands, and Ceylon. The 



