22 G. LINDSTRÖM, HELIOLITID^. 



to evade this dilemma by a suggestion ^ which he deduced from von Koch's above men- 

 tioned observation on the transformation of the siphonozooids and he was supported by 

 Neumayk.'- Waagen says that the siphonozooid in transforming into an autozooid required 

 much more room and »it might then well be imagined .... that ... to make room for 

 the new individual thus formed, the surrounding siphonozoids die and that the lirst sign 

 of this beginning decaj'^ is just the thickeniug of the outer walls, which are destined to 

 form together the wall of the new autozooid». Does this mean that the tubuli ai^ound 

 the new autozooid are absorbed and that only their outer walls remain to form the theca 

 of the new calicle? 



For the rest the thickening of the theca, of which Waagen speaks, is by no means 

 the beginning of the change in the coenenchyma, but on the contrary the last act of it. 

 And if it were as Waagen says, we should see only one of the »siphonozooids» enlarge and 

 most naturally the central one within the area affected. Instead, the tubuli there continue 

 for a while of the same size, and then it may be two or three contiguous ones in the 

 periphery which have grown larger.^ 



At last NiCHOLSON, who in his works previous to the third edition of his Manual 

 of Pateontology, published in 1889, does not make any mention of the coenenchymal 

 gemmation, seems there, p. 334, hesitate to accept full}' the interpretation of Moseley of 

 what may be called polygenesis as he says that the conversion of a gi"oup of imperfect 

 polyps into a single polyp is a »remarkable» phenomenon. Then he continues in the same 

 raanner as Waagen, that it is only a single siphonozooid which becomes converted into 

 an autozooid. 



There is now not much need to confute these statements since Bourne, von Koch 

 and others have demonstrated that there are no siphonozooids existant in Heliopora. 

 Bourne has,* though assuming the affinity of Heliopora Måth Heliolites, shown, as it uie 

 seems, upon clear evidence, that the coenenchymal coeca of Heliopora »are not of the 

 nature of degenerate siphonozooids». Consequently no single autozooid could here develop 

 out of one, still less of a plurality siphonozooids. Moreover, on jiccount of its sceleton 

 Heliopora must be considered as a highly aberi'ant member of the Alcyonaria. 



2. Tntracalidnal gemmation. Of this I have above at page 13 given notiee and below 

 in the deseription of Heliol. interstinctus (]j1. i fig. 34, 35 and also ])1. iv f. IT), pl. viu 

 lig. 28) all particulars. In a certain way it is a variety of the coenenchymal gemmation, 

 as no new buds arise before the coenenchyma has been sufficiently develoj^ed ;iround the 

 raised calicle. And both sorts of gemmation have the comnion feature of originating out 

 of the börder zone. Its difiference from coenenchymal gemmation consists in itis originating 

 first a coenenchyma within the tubularly elongated calicle, tlien out of this new calicles. 



' Palseontologia Indica, Seit. XIII, Proftnclus liniHRloiie Fossils ji. 90H. 



- Thierstämme )>. .431. 



■'■ I cannot fiiul liow iny olisnrvation tliat tlio ii(ily)iierite and llio calir-le ijropor in incipiont oolouios are 

 formed lieforc tlio coonencliyma can not tlio least, as WAAfiEN seems to tliink, sn]>i)Ort a siipiiosition of liis that the 

 cofineiicliymal tubes (= ;raesopore3.) are tlie first and tliat tlie »largo tulies- in Fistnlipora are develoiied oul 

 of tlicni. I did not ofcupy myself witli tlie Fistnlipora» and tiie reality in Heliolitida- is in direct eonti'adiction 

 to what 1)8 says. 



' Stiiiéture and Affinities of Heliopora foerulea, IHlliJ p. 472- 47."). 



