854 ORDER TENTACULIFERA-ACTINARIA. 



similarity as exists, M. Fraipont* has succeeded in eliciting, through a careful study 

 of its structural and developmental history, many points of high interest not hitherto 

 recorded in connection with this very remarkable generic group. Among the most 

 important data thus determined must be mentioned his demonstration that this 

 form, in common with the more normal Acinetidse, possesses a well-developed 

 nucleus or endoplast. Such a structure, while not visible during life, and not hitherto 

 observed in any other species of Op/iryodendron, was rendered distinctly visible in 

 examples first treated with absolute alcohol, and afterwards immersed in picrocarmine. 

 Although not observed to contract, M. Fraipont has no hesitation in identifying the 

 vacuolar space, in most cases conspicuous towards the anterior extremity of the 

 body, as identical with the pulsatory contractile vesicle of the ordinary Acinetidae and 

 other Infusoria. In Podophrya gcmmipara, as attested to by Hertwig, an interval of 

 several hours may elapse between the systolic contractions of this vesicular structure, 

 and may consequently in the present instance recur at even longer intervals. With 

 reference to the vermiform zooids, M. Fraipont adheres to Claparede and Lach- 

 mann's original interpretation that they represent an immature condition only of the 

 proboscidiform individuals, and supports his decision with figures and descriptions 

 of transitional phases between the two. These vermiform zooids, as in O. abietinum, 

 are derived as gemmules from the proboscidiform units, into which a portion of 

 the parent endoplast is extended ; in this species, however, the gemmules either take 

 a vermiform contour or pass directly to the proboscidiform condition. The navi- 

 cular refringent corpuscles enclosed within the parenchyma of this species in 

 common with O. abietinum, M. Fraipont is inclined to identify with the trichocysts 

 of the Infusoria Ciliata. 



Ophryodendron multicapitatum, S. K. PL. XLVIIlA. FIGS. 26-31. 



Bodies of primary proboscidiferous zooids variable in shape, ovate, sub- 

 spherical, or pyriform, distinctly pedicellate when young or half-grown, 

 sessile in their adult state ; the adult zooids usually supporting as many 

 as four subterminally developed proboscidiform organs, whose distal 

 extremities bear from thirty to forty cirrose appendages ; the secondary 

 or vermiform zooids elongate, developed in company with a variable number 

 of ovate or subspheroidal gemmules around the bases of the proboscidi- 

 form organs ; endoplast or contractile vesicle not observed. Height of 

 adult proboscidiferous zooids 1-300". 



HAB. Salt water, attached to the limbs of an Isopodous crustacean. 



This very rematkable form was obtained by the author in March 1879, during a 

 few days spent in the collection of marine specimens among the group of rocks lying 

 midway between France and the island of Jersey, known to fishermen as the " Min- 

 quieres." Some dozen specimens in various stages of development were thus obtained, 

 attached chiefly to the antennae and ambulatory appendages of a small Isopod 

 apparently most nearly allied to the fresh-water genus Asellus. The most remarkable 

 feature concerning this species, which will be immediately recognized, consists of the 

 abnormal number of proboscidiform organs, these in the adult examples numbering no 

 less than four, and two or three being commonly present in those less developed. 

 In a like manner, the number of germs developed simultaneously upon the anterior 

 border of the body usually coincide more or less nearly with that of the probosces, 

 and in both instances exceed what obtains in any species hitherto described. The 

 metamorphoses undergone by the anteriorly developed germs after detachment from 

 the parent zooid, and prior to their arrival at the adult state, are of considerable 

 interest. In the first place, as shown at PI. XLVIII. Fig. 29, the body, as in the 



" Acinetiens dc la Cote d'Oslencle," 'Bull. Acad. Eruxelles,' 1879. 



