JVLV 17, 1903.] 



SCIENCE. 



81 



directives being present. But in fissiparous 

 forms, since there is no tendency to reproduce 

 directives in the regenerative growth which 

 succeeds the division, all of the polyps of a 

 colony, with the exception of two, will lack 

 directives and will show little regularity in 

 the arrangement of the mesenterial pairs. 



What might be regarded as a third mode 

 of non-sexual reproduction has been observed 

 in the perforate corals Madrepora and Porites 

 and has been aptly termed by Duerden fissip- 

 arous gemmatioih since the mesenteries of 

 any one polyp are partly derived directly from 

 the parent and are partly new formations, the 

 process in this respect resembling ordinary 

 fission, while it also resembles gemmation in 

 that the original hexamerous arrangement of 

 the mesenteries and the typical number of 

 directives are retained as a result of growth 

 processes which precede the fission. 



The careful study of the madrepores, how- 

 ever, has not yielded such important taxo- 

 nomic results as might have been expected; 

 their soft parts do not present as much variety 

 as do those of the actinians. But by extend- 

 ing his observations over so great a number 

 of forms Duerden has been able to establish 

 as fundamental certain facts in the morphol- 

 ogy of the corals which throw some light upon 

 their position among the Anthozoa. The fact 

 that the corallum appears only after the de- 

 velopment of the first cycle of mesenteries 

 seems to warrant the conclusion that the 

 corals are derived from non-coralligenous hex- 

 amerous forms. In other words, it indicates 

 that the Hexactinise, Zoantheas and Madre- 

 poraria are all traceable to a common hexam- 

 erous ancestor, and that after the differentia- 

 tion of the Zoantheae the Madrepores and 

 Ilexactinians continued together for a time 

 and have for a fundamental distinction only 

 the development or non-development of a co- 

 rallum. The Madreporaria are merely Hex- 

 actinisB which secrete a corallum. This is 

 by no moans a novel view of the relationship 

 of these two groups, but it is one that is em- 

 phasized by Dr. Duerden's careful and inter- 

 esting observations. 



But the question whether the derivation of 



the Madreporaria from the llexactinise is 

 mono- or polyphyletic still lacks a decisive 

 answer. The uniformity of structure shown 

 by the madreporarian polyp seems to argue 

 for a monophyletic origin, although it by no 

 means excludes the other possibility. It is 

 exceedingly interesting to note that of all the 

 actinians, those which approach nearest to the 

 corals in structure are, as Duerden himself 

 has elsewhere pointed out, such forms as Ac- 

 tinotryx and Ricordea, forms, that is to say, 

 belonging to the stichodactyline group of ac- 

 tinians, having more than one tentacle arising 

 from certain of the endocoelic spaces. And 

 yet such an arrangement of the tentacles is 

 not known to occur among the corals. It 

 would seem either that the corals are derived 

 from actinine forms with regularly cyclical 

 tentacles, and that the similarities which the 

 actinians mentioned above present to them 

 are due to similar conditions of life, the ac- 

 tinians molding themselves over foreign 

 bodies very much as a coral ployp is molded 

 over its corallum, or that we may yet discover 

 stichodactyline corals. So far as our present 

 information goes we are justified in assuming 

 only an actinine origin for the corals, but if, 

 as suggested, the similarities of Actinoiryx 

 and Ricordea to the coral be due to similar 

 life conditions, it would be easy to understand 

 how the formation of a corallum would lead 

 to very general uniformity of structure in 

 forms of different ancestry, and would permit 

 a supposition that the coralligenous forms 

 might have arisen independently from several 

 actinine groups. 



A decision on these points must be left for 

 future investigation, which, it is hoped, will 

 be abundantly stimulated by Dr. Duerden's 

 most painstaking and important work. 



J. P. ]^rcM. 



SOCIETIES A\D ACADEMIES. 



NEW YORK ACADEMY OF SCIENCE. 



SECTION OF ANTHROPOLOGY AND PSYCHOLOGY. 



The regular meeting of the section was 

 held on April 27 in conjunction with the 

 New York branch of the American Psycho- 



