26 



3° Probably identical with Suberites zoilsoni: Alcyonium purpureum , Spirastrclla areolaia, 



S. massa, S. bonncti, Hymeniacidon pulvinatus, 426 a -c, 1045, 1949- 

 4 Identical with Spirastrella vagabunda : S. congenera, S. punctulata, S. solida, S. carnosa, 



S. teutorioides, 948 a-f. 

 5 Identical with Suberites inconstans var. globosa and var. maeandrina: Hymeniacidon augulata, 



Vioa florida, g8, 612 a, 931 a-b, 964 a-b, 966 a-b, 977 and 1047- 

 6° Identical with Suberites inconstans var. digitata : 1365, 1971, 1975, 2049- 



Consequently we have six groups, which each contain several "species". At any rate 

 we should have to reduce the number of these "species" to six, or, admitting Dendy's views 

 in considering "globosa" (resp. " maeandrina ") and „digitata". as mere "varieties" o( S. inconstans, 

 only five. The Siboga collection contains, however, a number of other specimens which form 

 connecting links; herewith a specific distinction becomes impossible. It cannot be denied, however, 

 that on the whole the "species" of each group are mutually closer related than with others. 

 I do not wish to consider these groups as "varieties", since this term, vague as it is, is not 

 always used in the same sense. For similar reason I will rather avoid to apply the term "forma" 

 Lindgren (1898) speaks of a forma libera and a forma excavans in the case of Spirastrella 

 aurivillii. As I am of opinion that the species of the genus Spirastrella do not perforate 

 calcareous matter, are not boring sponges, it might give new confusion in using the term 

 forma in our case. Bidder suggested (1902 p. 381) the word "metamp" for certain cases in 

 which specimens were different from the type species. If I am not mistaken, Bidder wishes 

 to apply the term metamp for the case one has reason to suppose that the difterence is due 

 to external circumstances, such as temperature, constitution of the medium, the bottom of the 

 sea etc. and that the variation is not congenital. In our case this is exactly what for the moment 

 cannot be made out. Under such circumstances it seemed to me better to use the indifferent 

 term tropus^). Thus for instance, Spirastrella cunctatrix, papillosa, panis, insiguis, g2a-l, 426c! 

 belong to one tropus; Suberites wilsoni, Alcyonium purpurcum, 426 a-c, 1045 to another. 



We have seen before that the specimens of the latter tropus belong to one species, the 

 oldest name of which is Alcyonium purpureum, which Ridley correctly replaced by Spirastrella 

 purpurea. And since no other specific name of specimens of another tropus has priority this 

 is the name for our sponge. For I have demonstrated that many of the other "species" are 

 identical with Lamarck's sponge and we will find still more arguments herefor in the course 

 of this paper. For the sake of convenience I will state now already that I distinguish seven 

 tropi, which I call tegens, tuberosa, digitata, pyramidalis, tubulifcra, coucrescens and glaebosa. 



To tropus tegens belong: dccumbeus, bistellata, semilunaris, 1031, 1455 a-c, 1945, a. o. 



To tropus tuberosa: cunctatrix, papillosa, insiguis, g2a-l, 4260, a. o. 



To tropus digitata: vagabunda, congenera, punctulata, 948 a-f, a. o. 



To tropus pyramidalis: wilsoni, areolata, purpurea, 426 a-c, 1949, a - °- 



To tropus tubulifera : inconstans var. digitata, 1365, 1971, 1975, a - °- 



To tropus coucrescens: Jiorida, 305 a-d, 612 b-d, 1047, 1341 a-c, a. o. 



1) TfOTro?, direction, sort, manner, character, peculiarity. 



