q/Poljparium ambulans, Korotneff. 211 



referred to liereafter, sucli a form, with a sufficiency of food, 

 would enter upon a process of growth, such as is assumed by 

 Korotneff in the case of Polyparium ambulans^ and would 

 then more and more develop the band-like form. 



But what is to be regarded as the original form from which 

 Polyparium amhulans might have been derived? Notwith- 

 standing Lacaze-Duthiers's * observations upon the Actinia- 

 like living creatures which separated off from a GaTyophjllia^ 

 polyps forming hard parts may well be left out of considera- 

 tion in this case. Such structures as the acetabula standing 

 on the foot-surface are known in no Malacodermatous form, 

 so far as I am aware. To assume that these structures might 

 have become developed in Polyparium amhulans under its 

 peculiar conditions of existence is a convenient mode of 

 escaping from the difficulties which at present assail us, 

 perhaps only in consequence of our insufficient knowledge 

 of Actinid forms. 



On the other hand, the " buccal cones," which I have 

 interpreted as tentacles, furnish a probable indication of the 

 Sicyonidse, Liponemidee, and Polyopidas described by K.. 

 Hertwig. Now all these animals, without possessing any 

 close affinity to each other, are inhabitants of the deep sea. 

 May the " buccal cones " of Polyparium amhulans possibly 

 indicate that the starting-point of its development is to be 

 sought in a deep-sea form of Actinia? 



But then the question already touched upon cannot be 

 avoided, namely whether Polyparium amhulans is to be con- 

 sidered an animal produced by regular development, or whether 

 it is to be placed among those animals, at present certainly but 

 imperfectly known, which, under the influence of external 

 conditions, are brought into a course outside regularity and 

 become developed further in this course. I would denominate 

 such animals paranomally developed, in opposition to . the 

 regularly or eunomally developed animals. Or, to express 

 the case otherwise, Is Polyparium amhulans a phylogenetically- 

 developed species at some time propagating by sexual pro- 

 cesses ? or have we in it a form diverging from the typical 

 form, produced in each individual case by the action of 

 external conditions, and which either dies out as such in each 

 instance or, perhaps, may produce similar organisms by 

 asexual reproduction ? 



I may adopt this last case as the conclusion of these specu- 

 lative considerations, and in accordance therewith interpret 

 Polyparium amhulans as a fragment separated off from a 



* Loc. cit. p. 382. 



