272 AGALMIDAE. 



Agalmidae Hkandt, 1835. 



The history of the Agahnidae has been reviewed in detail by Bedot COG) 

 in his revision of the family. The species here included form a homogeneous 

 group. But though several of them are now well known the two students who 

 have attempted to revise theni s'nce Haeckel ('88b), have come to totally opposite 

 conclusions as to what charac rs are generic and how manj' genera deserve 

 recognition. Bedot ('96) concluded that the most important systematic char- 

 acter within the family is the structure of the tentilla, and that general "habitus," 

 whether long and contractile, or short and stifi', and form of the l^racts whether 

 thick or thin, are of subordinate value only. Proceeding on this basis, he 

 recognizes eight genera and thirteen species. Schneider ('98) accepts onlj- one 

 of Bedot's genera, Anthemodes. All the other species, or supposed species, 

 according to his view, properly fall provisionally into three genera, Stephanomia, 

 Agalmopsis, and Cupulita. Instead of using the tentilla as generic characters, 

 he states that they are entirely worthless, and bases his classification "einzig 

 und allein in Riicksicht auf den characteristischen Habitus dreier Artgi-uppen" 

 ('98, p. 118) that is to say, his Stephanomia comprises short, stiff forms; his 

 Agalmopsis is longer, softer, and more contractile; while his Cupulita, with 

 extremely extensible axis and loosely arranged bracts, is the end of the series. 

 The adoption, entirely or in part, of one or other of these schemes, depends on 

 the relative value of tentilla and of general form. I have been unable to find 

 any other characters which could possibly be considered of generic value, in 

 any of the five species which I have studied. 



General form, particularly contractility of the stem and shape of the bracts, 

 was long ago used by Haeckel ('88b) to distinguish two subfamilies of Agalmidae, 

 i. e., Crystallodinae and Anthemodinae. But a critical examination of this 

 character shows that it is not so significant as he supposed. It is true that 

 every species, so far as known, is comparatively constant in this respect. But 

 the various species, from the shortest and most rigid, to the longest and most 

 contractile, form an unbroken series which is divisible by purely artificial lines 

 only. Furthermore, relative length can not be correlated in a natural grouping 

 with any other characters. Thus species with tricornuate tentilla may be 

 either stiff, or soft and slender; and the same is true of those with unicornuate 

 tentilla. "Habitus," then, seems to me, as to Bedot, quite worthless as a 

 generic character, although it is no doubt one of the most useful field marks 

 for specific determination. 



