79 



In the genus Electra the median acropetal spine is much branched in E. helliila, 

 while the peculiar unilateral covering spine, which appears in the family Scrupo- 

 cellariidae is branched in a number of species, as in Scriipocellaria reptans and 

 Menipea (uulcala. Further, branched oral and marginal spines appear in larger 

 or smaller nundier in Mcnihrdniporina cornujcra, M. protecla, in several varieties 

 of Microporelld Maliisi, in two species of the genus Clutpeiid {(I. (iiiniiliis and C. 

 cerincornis), in Hiunlupora radicifcra and in some Species of the family Cribrilini- 

 dne. The differences mentioned in the shape of the spine have, as will be seen 

 from the given examples, generally a very slight systematic importance, and are 

 not even always an expression for a difference of species, hi the same way as 

 there is hardly any family or genus, except those very poor in species, in which 

 all the members have spines, so there are hardly many species, in wliich the 

 number of spines is constant, and in many cases the variation is very consider- 

 able. We may give here a few instances of the variation in number of the spines 

 in genus and species, hi Smitlina the number varies between and 8, in Escha- 

 rvlUi between and 10, in Chaperia between and 8 and in Callopora between 

 and 13. hi Electra inonostacljiis the number varies between 1 and 18, and even 

 the one is not always present, in E. pilosa between 4 and 12, in Callopora liiiealu 

 between B and 12, and in Biujulu Murraijana between 3 and 8. hi discussing the 

 systematic importance of the spines, we must still notice that the family Cribri- 

 linidae is based solely on the mutual relation of the marginal spines, and that a 

 plate-shaped or branched covering spine only appears in the family Scrupocellarii- 

 dae. To this we must still add that this spine is far from being found in all the 

 species of the family, and that the family Cribrilinidae is undoubtedly not a 

 natural one. hi contrast to the generally great inconstancy and variation of the 

 spines, it may be mentioned that marginal spines are always lacking in numer- 

 ous families, which are mostly rich in species, e. g. Farciniinariidae, Cellulariidae, 

 Sleiianopori'lUdne, Thalamoporellidae, Adeonidni-, Calcnariidae, C.clleporidae, Hippo- 

 Ihuidae, Myiiozoidae and Tubucclbiriidae. 



Finally, we may briefly refer to a new Callopora species, from the F'ieroes, 

 which apparently shows the largest amount of variations in the numtjer, struc- 

 ture and mutual relation of the spines, which have yet been found in any Bripzoa. 

 While some zoa'cia only have 4 short spines, others have a veiy varying number 

 of longer ones, which sometimes have the same breadth in their whole length, 

 sometimes the tip expanded or bifurcated. These longer spines in more or fewer 

 zooecia may be united with one another to form a cover, pierced by transver.se 

 furrows, just as we lind in the species of the genus Membraiiiporelld. 



The primary aperture. In a nundier of species we meet two ditferenl forms 



