HYDROIDA 57 



transverse belts. This jieculiarity we find slighlh- indicated even in some Botigahivilliidac. But only 

 in the Eudfiidriidac it has become a character plainly distinctive. Further, the endoderm in the well 

 defined hypostome shows the same strncture as in the thecaphore Indroids, and is more strongly differ- 

 entiated than in the Bougaiitvilliidat\ the indifferent cells having grained the ascendency, and the number 

 of the mucous gland cells having been reduced to a miuiniuni. Whether these peculiarities are indic- 

 ative of a nearer relationship between the Eudriidriidac and the thecaphore liydroids, is a question 

 which it would here be out of place to enlarge upon. 



The Eudci!driida(\ with their frequently dimorphic development of the stinging cells, also pre- 

 sent a parallel to the Sfylnsfrridac. Besides the small rodformed stinging cells characteristic of all 

 Fill/era^ we also find in several species larger narrowl\- o\al ones, bearing a strong resemblance to 

 those of the Stylastrridac. The latter are large, but of the same shape as the small stinging cells of 

 Myriotliila. We i:)robably here face a phenomenon of convergency, the reason of which, however, at 

 ihe jnesent stage of our knowledge of the biology of the Coelenterata, we cannot account for with 

 anv certaintv. Where\-er the larger stinging cells occur in the Endciidriidac they are accumulated in 

 particular stinging organs. 



Eudendrium Iihreni)erg. 



Upright colonies with branched hydrocanlus. The polyps are broad and distinctly set off from 

 the stem, which is covered with a vigorous chitinous perisarc. The polyp has a single whorl of fili- 

 form tentacles. Above the tentacle whorl the p"l>'p is suddenly tapering and ends into a capitate or 

 trunipetshaped proboscis, which is seated, with a narrow base, above the tentacle whorl. The gono- 

 pliores are developed on normal or reduced polyps, or placed singly on the branches. 



Kiihn (1913, p. 48) states that the polyp tentacles of EitdnidriiDii "nach einander vorsprossen 

 nnd dadurch sich als Angehorige verschiedener Wirtel zu erkennen geben". Later on (1. c. p. 247) he 

 again mentions this j.)eculiaritv as a refutatory argument against the adoption of a nearer relationship 

 to the thecaphore hydroids; in the passage last quoted he apparently bases his opinion essentialh' on All- 

 man (1872). A closer inquiry, on new material, gave no hold to the statement of A 11 man and Kiih n that 

 the tentacles should appear successively. In the numerous colonies examined of Eiidcudrinin ramcuDi 

 (Pallas) and Eudcndrm)ii IVrigliti Hartlaub it could be ascertained that all the tentacles appear 

 simultaneoush'. This suggests that the observations of All man may rather dej^end on accidental cir- 

 cumstances, and that no special importance must be attached to them as reminiscences of manyrowed 

 tentacle-whorls of the ancestors or as proofs of a nearer or remoter relationship to the Boitgainvil- 

 liidac or to the thecaphore hydroids. 



Eudendrium rameum (Pallas) Thompson. 



1766 Tiihiilaria raiiica^ Pallas, b'lenchus zoophytorum, p. 83. 



1844 Eludrndriuin rantciiin, Thompson, Report on the Fauna of Ireland, jx 283. 



1887 — ramostini^ Bergli, Karahavets goplepolyper, p. 332. 



The IngoIf'Expcdilion. V. 6. 



