GENUS OPHRVODEXDRON. 853 



A full account of this interesting and very distinct species was communicated by 

 Mr. Th. Hincks to the ' Quarterly Journal of Microscopical Science ' for January 

 1873. The regular cup-shaped Ijody seated on its slender curved pedicle at once 

 distinguishes the primaiy zooids of this form from those of the preceding one, while 

 in addition, the group of tentacular processes, depressed during extension in a radiate 

 rather than in a brush-hke manner, at the distal extremity of the proboscis, are 

 much fewer in number and apparently of equal size, instead of bemg longest at 

 the base and gradually diminishing as the apex is approached. The secondary or 

 vermiform zooids closely correspond with those of O. abietintim, and are only 

 distinguishable from them by their curved instead of rectilinear pedicle. In one 

 instance two zooids of this denomination were observed with their pedicles united 

 for a portion of their length, and in all probability represented an instance of 

 longitudinal fission. These secondar>' vermiform zooids, of both this and the 

 preceding species, are described by Mr. Hincks as being particularly active in their 

 movements, constantly swaying themselves gracefully to and fro in all possible 

 directions, now sweeping the surrounding water, now passing the oral extremity of 

 the neck over the surface of the polypary on which the colony is planted, and now 

 reaching over towards the proboscidian zooids, and bringing themselves into frequent 

 contact with the trunks and probosces of this series. The primary or proboscidian 

 zooids are, on the other hand, comparatively quiescent, restricting their motions 

 chiefly to the extension and retraction of their trunk-like proboscis, but which may 

 be thus extended or withdrawn with amazing swiftness. 



The species of Ophryodemiron described by Koch* under the title of O. pcduncu- 

 latum, and obtained by him at Messina, is, as recognized by Fraipont, apparently 

 identical with Mr. Hincks's type. 



Ophryodendron Belgicum, Fraipont. Pl. XLVIII. Figs. 36 and 37. 



Proboscidiform zooids clongate-pyriform or clavate, often furrowed 

 anteriorly, attached by a sucker-like expansion of the more attenuate 

 posterior extremity ; proboscis evertile to about one-half of the lenjjth of 

 the extended body, its distal end bearing from five or six to not more than 

 eight tentaculoid cirri ; parenchyma opaque, frequently inclosing numerous 

 refringent navicular corpuscles ; endoplast, rendered visible only by the 

 action of reagents, in adult examples more or less irregularly branched ; a 

 vacuolar space, apparently representing the contractile vacuole, usually 

 developed towards the anterior region of the body, and occasionally a 

 second one near the posterior extremity. Vermiform zooids subcylindrical 

 or clavate, seven or eight times as long as broad, affixed posteriorly by a 

 slender rigid pedicle when young, but subsequently attached in a sessile 

 manner ; parenchyma resembling that of the proboscidiform zooids, and in a 

 similar manner frequently inclosing refringent corpuscles ; endoplast and 

 vacuolar spaces as in the proboscidiform examples, but the first-named 

 structure less complex. Length of proboscidiform zooids 1-400" ; of 

 vermiform zooids 1-400". 



Hab. — Salt water : Ostend, on the hydrothecse of Clitia voliibilis. 



Apart from its size and habitat, the chief distinction between this type and 

 Ophryodendron abietinum would seem to subsist in the less luxuriant development 

 of the tentacular appendages of the proboscis. Notwithstanding, however, such 



* " Zwei Aciueten auf Plumularia selace.i.'' Jena, 1S76. 



