850 ORDER TENTACULIFERA-ACTLWARIA. 



Although the further development of the vermiform into the proboscidiform zooids has 

 not so far been determined, it is clear that little beyond the everting of the neck-like 

 anterior region of the former is requisite to bring about such a result. The view 

 here expressed is substantially supported by the evidence given by Fraipont in 

 connection with his ver)' recent description of Ophryodendron Bdgicum, in which 

 type, indeed, he records tlie occurrence of and figures intermediate phases. 



The affinity of the members of the genus Ophryodeiidroti with the normal 

 Acinetce is predicated through the assumed correspondence of the proboscis-like 

 prolongation and terminal cirri of the typical zooids ynih the suctorial tentacles 

 of the latter. No evidence has, however, yet been adduced showing that these 

 filaments or the extensile proboscis itself possess a similar suctorial capacity, 

 nor, indeed, is it yet known in what manner the organism grasps or incepts its food. 

 Pending the satisfactory elucidation of this most important point, it seems most 

 reasonable to premise that food-substances are seized by the brush-like filamentous 

 tuft or distal end of the proboscis itself, and then withdrawn with it into the 

 parenchyma of the body. Should this view prove correct, the retractile proboscis 

 will be shown to be homologous with the non-suctorial but adhesive tentacles of the 

 genus Ephdota, concentrated, however, into the form of a single and proportionately 

 larger terminal tentaculum. In this connection it may be further submitted that 

 the transverse subspirally disposed rug£e that form so conspicuous a feature of the 

 proboscis of Ophiycdmdron when examined under high magnification, are both 

 functionally and morphologically identical with the delicate granular fibrillje which in 

 a similar manner encircle the individual tentacles, whether suctorial or simply 

 adhesive, of various ordinary Acinetid^, such as Podophrya elongata and Hemiophrya 

 gemmipara. 



Ophryodendron abietinum, C. & L. Pl. XLVIIIa. Figs. 13-15 .and 32. 



Primary or proboscidiform zooids cup-shaped or pyriform, with a cleft 

 on one side of the anterior margin, tapering posteriorly, and adherent by 

 an annular disk-like expansion ; proboscis long, slender, cylindrical, highly 

 extensile, pointed at its apex, and bearing a brush-like tuft of twenty or 

 thirty tentacular filaments ; secondary or vermiform zooids (larvae .') ovate 

 or vermiform, rounded or slightly pointed posteriorly, produced at the 

 opposite extremity into a long, slender, tubular neck, and usually mounted 

 on a straight setose pedicle ; parenchyma of the body generally enclosing 

 innumerable minute refringent navicula-shaped corpuscles. Length of body 

 of primarj'-or proboscidiform zooids, without the proboscis, 1-175" to 1-30" ; 

 of the vermiform zooids 1-150" to 1-30". 



Hab. — Salt water, attached to the polyparies of Serttilaria, Plumiilaria, 

 and other Hydrozoa. 



Oval ciliated embryos were liberated artificially by pressure from the paren- 

 chyma of examples of this species examined by Claparfede and Lachmann. This 

 ciliation is limited to one surface only of the embryo, as occurs in Podophrya 

 cothurnata, Hemiophrya gemmipara and Dendrocomdes paradoxus, and may be thus said 

 to follow a hypotrichous plan. The further development of these embryos remains 

 to be traced, and is likely to be of much interest. In addition to the ordinary pro- 

 duction by gemmation of the vermiform zooids, Claparfede and Lachmann figure an 

 example in which a proboscidiform zooid is in course of production in a somewhat 

 similar manner from another of the same form. On reference to the figure cited, 

 however, one is inclined to interpret this example as illustrating the phenomenon 

 of longitudinal fission rather than that of peripheral gemmation. The specific name 

 of abietinum has been conferred upon this species by its discoverers, with reference 



