and their Relationship to the Corals, 7 



Mediis£e) ; 3. Ctenopliora (Ciliograda). All the animals of 

 these three classes agree not only in the characteristic formation 

 of the nutritive vascular system, but also in the possession of 

 urticating organs, for which reason Huxley grouped them to- 

 gether as Nematopliora. These characteristic urticating organs 

 are entirely deficient in all true sponges. The absolute defi- 

 ciency of the urticating organs in all sponges^ and their constant 

 presence in all corals, Hydromedus^, and Ctenophora, is at 

 present the sole morphological character which sharply and 

 decidedly separates the first class from the last three. I have 

 tlierefore, in my ' ]\Ionograph of the Monera,' and subsequently 

 in my ' Natural History of Creation,' included the three last- 

 mentioned classes under the old name of Acalephoi or. Cnidce 

 (nettle-animals). Even Aristotle comprehended under this 

 denomination the two characteristic primary types of the 

 group, the free-swimming Medusce and the sedentary Actinice. 

 Moreover the distinctive character of the nettle-animals, 

 namely the possession of urticating organs, is just as clearly 

 expressed by this denomination as by Huxley's name Nema- 

 topliora. 



We should therefore have to divide the stem or phylum of 

 the Zoophytes {Coelenterata s. Zoophytci) into two primary 

 groups (subphyla or cladi) — 1, Sponges {Spongice s. Pori- 

 fera)j and, 2, Nettle-animals {Acalejyha'^ s. Cnidci'., s. Nemato- 

 plioroi). The latter would divide into the three classes of the 

 Corals, Hydromedusfe, and Ctenophora. Among the sponges 

 we might provisionally distinguish as two classes the Auto- 

 spongice and the fossil Petrospongice, as hitherto these two 

 groups have not allowed themselves to be brought into near 

 connexion either in the whole or in detail. Among the Auto- 

 spongiaa the Galcispongice would form a distinct subclass or 

 legion. 



We might perhaps go even further, and, supported by the 

 very near relations of affinity of the sponges and corals, speak 

 in favour of the following division of the Coelenterata : — 



Cladus I. Bush-animals (Thamnoda). 



Class 1. Sponges {Spongice). 

 Class 2. Corals [Corallia). 



Cladus II. Sea-jellies (Medusa). 



Class 1. Umbrella-jellies {Hydromedusce). 

 Class 2. Comb-jellies {Ctenophora^} . 



Time only can decide which grouping best corresponds 

 to the natural relationships, when the genealogy of the 



