7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 25 



close its tentacles over this crab. Crabs of other species placed among the ten- 

 tacles attempted to escape, the tentacles closed over them and if any appen- 

 dages were lost they were immediately swallowed by the anemone. 



Pax(') describes from the West Indies Gyrostoma 1 n. (being the first record 

 of G. from the Atlantic Ocean), Cystiactis 1 n., Bunodosoma 1 n., Aiptasia 

 1 n. and Palythoa 1 n. He regards as belonging to Aipt. only those Sagar- 

 tiidae in which the sphincter is entirely absent (contrary to Haddon) ; he divides 

 the species of A. into two groups; (1) Psilonemata, including those with 

 smooth tentacles, e.g. leiodactyla n., and (2) Dactyliophorse in which the ten- 

 tacles bear annular or spiral thickenings, e.g. annulata. 



Me Murrich( 2 ) distinguishes, in the Ceriantharia, two sets of mesenteries, 

 (1) the protocnemes, consisting of the first 4 couples, in which the order of 

 succession (which, starting from the ventral line is 3, 1, 2, 4) is similar to that 

 occurring in the majority of Hexactinians, (2) the >deuterocnemes, consisting 

 of all the remaining pairs, which appear successively in couples in the dorsal 

 inter-mesenterial chamber. The sequence of the protocnemes points to an 

 ancestral stage with 8 mesenteries from which the Ceriantheae have branched 

 off in one direction and the Hexactiniae and Zoanthese in another. Judging 

 by the sequence of the mesenteries, the single siphonoglyph of Cerianthids 

 has the same orientation as in Zoanthids and is therefore ventral. In Cerianthus 

 membranaceus, americanus, Lloydii and Verrillii the telocnemes (the con- 

 tinuous mesenteries* of earlier writers) are the second couple. In Pachycerian- 

 thus Benedeni the telocnemes are the 4th couple, ftmbriatus and monostichus (n.) 

 in the Siboga collection show a similar condition and in oligopodus, cestuarii 

 and Johnsoni and in Botryanthus Benedeni the arrangement is essentially the 

 same. In the larval forms Dactylactis , Arachnactis and Ovactis acontia are 

 borne by the 4th protocnemes, in Apiactis by the 2d, and in Peponactis by the 

 2d and 4th. In the more advanced larvae of the first group the 4th are also 

 the longest protocnemes. Of the deuterocnemes, the longer are termed macro- 

 cnemes (Heider's Genitalsepta) and the shorter brachycnemes (Filamentsepta). 

 In membr. the first quartette of deuterocnemes, i.e., that next the protocnemic 

 group, consists of Hrst a brachycneme (B), then a macrocneme (m), then a 

 2d brachycneme (b) somewhat shorter than the first, and then a 2d macro- 

 cneme (M) larger than the first; thus the formula of this and the succeeding 

 quartettes is B-m-b-M; a similar arrangement is found in C. Verrillii and in 

 fimbr. and monost. In C. Lloydii and americ. the formula is B-M-b-m. In all 

 species examined alternation of sterile and fertile mesenteries of the quartettes has 

 been found but in C. ambonensis, from the Siboga collection, all the mesenteries 

 are fertile, except the directive couple; in this species the arrangement of the 

 deuterocnemes appears to be in two rather than in fours. An examination 

 of the marginal tentacles of the quartettes shows that the tentacles of the two 

 proximal cycles correspond to the macrocnemes, and those of the two distal 

 cycles to the brachycnemes. The marginal tentacles correspond to the proto- 

 cnemes, but the labials do not present this relation. The processes of the 

 trefoil portion of the mesenterial filaments are distinct from acontia and 

 are termed craspedonemes. In P. fimbr. and C. americ. all the mesenteries, 

 except the directives, are provided with filaments of the same structure. In 

 the brachycnemes the uppermost portion of the filament has an almost straight 

 free border and is trilobed in section, then follows a portion in which the 

 border is much folded and apparently branched and throughout which the fila- 

 ment is single- lobed ; below this the free edge is almost straight and the single- 

 lobed portion of the filament is continued along it almost to its termination. 



g* 



