130 ACTINLE OF ALBATROSS EXPLORATIONS M' MURRICH. 



equivalent subgroups, juid. so far as the Actiuians arc concerned, by 

 the increase in the number of rcco.uni/ed ^ciuna and tlu'ir division into 

 I'aniilies, subl'aniilics, etc. The distin^iushing characters of Ihe \ arious 

 groups were drawn for the most part from external characters; impor- 

 tance, for instance, being ])laced njion the presence or al)senceofa 

 corallnm, wlu'tlier the base is adlierent or not, in th{> shape of tlie ten- 

 tacles, etc. Comi)aratively little was done toward attaining a tliorough 

 knowU'dge of the anatomical relationsldps of the various parts, or per- 

 haps it would be better to put it in tiiis way, that the atnitomical 

 knowledge tliat had been ac<piired was not suthciently extensive to be 

 (Mni)loyed for systematic i)ur])oses. The names of Ilollard, (Juatrefages, 

 llaime, Tln»rell, Teale, Sclincider and Hotteken, Stoliczka, etc., recall 

 imi)ortant additions to our knowledge of Actiniau inori)hology,but the 

 observations were not sufficiently extended to have suggested the im- 

 p(U'tauce that should have been attached to them. 



We are now in the third i»eriod, so brilliantly introdm-ed by the 

 brothers Hertwig with their monogra])h ou the Actiuians ('7U). The 

 ])eriod in its beginning overlaps, consequently, the second period. The 

 fundamental characteristic of Actiniau classitication at present is the 

 foundation wliich it i)ossesses on anatomical and phylogenetic features. 

 The arrangement of the mesenteries and their ontogenetic succession 

 arc the criteria whicli serve to separate the larger grcmps, and tliese 

 criteria have been extended, so far as our ])resent knowh'tlgc allows of 

 it, to the grou]) Anthozoa as a whoh\ The first step in this direction, 

 as stated, was made by the Tlcrtwigs ('7'.)), who, as a result of their 

 observations on a number of Actiniaria, arrived at the following con- 

 clusion : 



Hei dor Eintlu'ihing dor AnthozotMi siiid dii' Sopten in erster Keilie zu ))eriicksifli- 

 tigcn, abcr wenigor die Znlil jils viclmolir dcr H;ui, die Auordnuiig dirsclbon um das 

 Sclilnudrolir mid iliro Liitwickliing. Wciiu wir von diost'r (inmdlago iinsgchen, 

 werdt'n die Antliozocu voranssiclitlii'li in nielir als 2 Ordnnngcn zu zeifiillen sein. 

 Mlt Erfolg abev kann oin neues System erst daini anfgestellt werden. wcnn die ver- 

 schiedcnen Familien der Zoantharien, der Floisclipolypeu sowolil als dir Korallcn, 

 anf die Morphologie ibrer Septen, iiber die wir vielfacb nocb gar niibtswissen, nach 

 alien Rielitnngeu nntersucbt sein werden. 



The Hertwigs recognize liva> groups of Anthozoa, based on the charac- 

 ters indicated in the ab()^(' «iuotation, viz, the Actinida, lOdwardsiiP, 

 Zoanthida', Ceriaiitliida', and Alcyonaria. As regards the Madrepo- 

 raria, they do not commit themselves delinitely, recognizing the paucity 

 of the information with regard to their anatomical peculiarities at their 

 disposal: at the same tinu», however, tbey consider it probable that 

 when the recpiired infoi'mation is acquired the group of the Zoaiitharia 

 sclcrodemata will be split up, a large part of the corals being associated 

 witli the Actitudu', others, ])erhaps, with the Zoanthina\ and others 

 with Kdwai'dsia', while others, again, may show an ariangement and 

 structure of the mesenteries peculiar to themselves. 



