332 PORPITA. 



Pacific, except the problematical P. chrysocoma which more properly belongs to 

 the Malaysian region, must be referred to P. pacifica Lesson, a species, as I shall 

 later show, very distinct from the Atlantic P. umbella. 



To P. pacifica must likewise be referred the Pacific species of Haeckel's 

 genera Discalia and Disconalia, because the supposition that these forms are 

 monogastric, the sole ground for distinguishing between them and very young 

 Porpitas, appears to rest on no better evidence than the surface views of the 

 gonozooids. Of course to prove that these organs possess no terminal openings 

 would require the study of serial sections. Haeckel also mentions, as new, 

 P. australis; but since this name rests on neither description nor figures, nor 

 even any more definite localitj' than that it is a "Southern form" it is of course 

 a nomen nudem. 



Finally, before describing our series of P. pacifica, I may summarize brieflj* 

 our extremely scanty knowledge of the Porpitas from the Indian Ocean. The 

 oldest of these, as pointed out above (p. 329), is the P. porpita of Linne ( =P. 

 indica Bosc). There have since been described P. lutkeana Brandt, besides 

 Disconalia pectyllis Haeckel, which is undoubtedly the young of some Porpita. 

 As pointed out, P. chrysocoma may belong here, as do the specimens recorded 

 by me (: 04) from the Maldives under the name P. lutkeana Brandt, and from the 

 Malaysian region by Lens and Van Riemsdijk (:08) as P. umbella. Probably 

 all of these are identical, and ought to be united under the old name P. porpila. 

 Unfortunately our knowledge of them is not sufficient to give a definite answer 

 to the question whether P. porpita is identical with the Atlantic P. umbella, 

 or with the Pacific P. pacifica, or whether, as is possible, it is a species distinct 

 from either. 



The published descriptions, so far as they go, and my own insufficient exami- 

 nation of the Maldive specimens, seem to favor their union with P. umbella, 

 rather than their retention as distinct, as I formerly believed. The conclusion 

 that they are not referable to P. pacifica rests on the ground that though the 

 tubercles of the latter are prominent features even in macerated specimens, 

 no such structures were observed either on the "Siboga," or in the Maldive 

 specimens. The strongest evidence in favor of the view that P. porpita and 

 P. umbella are identical is the statement by Lens and Van Riemsdijk ( : 08, p. 123), 

 that they "found no difference whatever between them and Porpita linnaeana." 

 Unfortunately, however, their material was not of the best, and until better 

 series can be examined the identity of the Indian forms must remain in doubt. 

 A study of Porpitas from the region of the Cape of Good Hope, and a knowledge 



