X. On the Genus Porponia and Related Genera, Scottish National Antarctic 

 Expedition. By Professor Oskar Carlgren, Universitetets Zoologiska Institution, 

 Lund. Communicated by Dr W. S. BRUCE. (With One Plate and Text- 

 figures.) 



(MS. received August 12, 1913. Read January 19, 1914. Issued srpurati-ly March 30, 1914.) 



In an Appendix to the Actiniae of the Challenger Expedition, Pi. HERTWIG. 1882, 

 described a peculiar genus, Porponia, with two species, P. elongata and P. robusta, 

 which he characterises in the following manner : " Actiniarien (Hexactinien ?) mit 1 

 Schlundrinnen ohne Ringmuskel, mit diinnwandigen Tentakeln, deren Basen auf der 

 iiusseren Seite durch span gen formige Verlangerungen des Mauerblatts gestiitzt werden." 

 Partly owing to the badly preserved material, however, he did not venture to indicate 

 definitely its systematic position, though he considered it conceivable that it repre- 

 sented a transitional form between the Zoanthidae and the true Actiniae, or Hexactiniae. 

 HERTWIG expresses the following opinion regarding the systematic position of the 

 genus : " Die doppelreihige Stellung der Tentakel, die Abwesenheit vollstandiger 

 Geschlechtsepten (Macrosepten) und unvollstandiger, sterilen Septen (Microsepten) 

 sind Merkmale, welche an die Zoantheen erinnern, die Zahlen der Tentakel und der 

 Septen passen ebenfalls am meisten fur diese Gruppe, da sie weder von dem Numerus 6 

 wie bei den Hexactinien noch von dem Numerus 4 wie bei den Paractinien bestimmt sind. 

 Auf der anderen Seite nahert sich die P. elongata durch den Besitz von zwei Schlund- 

 rinnen wieder mehr den Hexactinien, unter denen sie am meisten mit den Antheo- 

 morphiden iibereinstimmt. Ich halte es daher fiir sehr wahrscheinlich, class P. elongata 

 eine Mittelform ist, welche den Ubergang von den Hexactinien zu den Zoantheen 

 bildet." Porponia possibly, he thinks, belongs to the Antheomorphidte, a family 

 supposed to be separated from the family Antheadae chiefly by the absence of a 

 sphincter and by the weak development of the musculature. 



Since R. HERTWIG described this genus, it has not been made the subject of any 

 close examination, nor for this reason has its systematic position been discussed in 

 detail. Yet it is only right to mention that M'MuRRlCH was inclined to refer the 

 genus Halcurias (Endoccelactis) to the neighbourhood of Porponia. " In fact," he 

 writes (p. 226, 1898), " 1 was inclined at first to associate it (Ilalcnrias) with Porponia, 

 and was only deterred from doing so by the simplicity of the arrangement of the 

 mesenteries." (That H<tl<-uri<ts possesses a peculiar arrangement of the mesenteries, 

 which agrees with what I have described, 1897, for the genus Endocaelactis, was not 

 known to M'MuRRiCH at that time.) 



A closer examination of the material which I received for investigation from the 

 (REPRINTED KKU.M THE TRANSACTIONS OK THK ROYAL SOCIETY OK KDINBDRQH, vol.. L., PP. 49-71.) 



