GENUS OPHRYODE'i^DRON. 849 



radiating muricate or echinulate tentacles. These last-named organs, viewed 

 separately, might in a like manner be appropriately compared with certain 

 echinulate hairs of the larvae of Derinestes lardarhis. 



Fam. II. OPHRYODENDRIDJE, S. K. 



Tentacles apparently united so as to form one or more distinct 

 proboscidiform appendages, the distal terminations of which are naked or 

 cirrate. 



Genus I. OPHRYODENDRON, C. & L. 



Animalcules mostly associated in colonies, but not organically connected, 

 attached in a sessile manner, or through the medium of a pedicle, usually 

 dimorphic, or including two distinct structural types ; zooids of the first order 

 ovate or pyriform, with a long, extensile and retractile,anterior, proboscidiform 

 organ bearing numerous flexible cirrose appendages at its distal extremity ; 

 zooids of the second order vermiform or flask-shaped, developed anteriorly 

 into a slender and apparently tubular neck having a small terminal orifice ; 

 contractile vesicle single or multiple; endoplast nodular or ramifying, 

 rendered visible only by the action of reagents. Increasing by gemmation 

 and by the production of ciliated embryos. Inhabiting salt water. 



Attention was first directed to the singular organisms referred to this genus by 

 Claparede and Lachmann, who discovered the type-form 0. abietinum on the coast of 

 Nonvay in the autumn of the year 1855, and included a description of it in their 

 Manoire on the Infusoria communicated to the Paris Academy of Sciences that 

 same year. Dr. Strethill Wright subsequently described a closely allied type under 

 the title of Coretliria sertularia in the 'Edinburgh Philosophical Journal' for July 

 1859 (description and figures reproduced in Pritchard's 'Infusoria,' ed. iv. 1861) ; 

 and the Rev. Th. Hincks has since given a more exhaustive account of O. abidiiium, 

 supplemented with the description of a third species, O. pedicdlatum, in the ' Quar- 

 terly Journal of Microscopical Science ' for January 1873. Several species have been 

 yet more recently discovered, but notwithstanding the attention bestowed upon them 

 by these various independent investigators, it cannot be said that the true nature and 

 affinities of the genus have as yet been accurately determined, and neither, on the 

 other hand, has a sufficiently satisfactory explanation so for been accorded concern- 

 ing the apparently anomalous phenomenon of dimorphism associated with the several 

 representatives of the genus. By Claparede and Lachmann, the vermiform or non- 

 proboscidiform zooids of O. ahktinum, though figured, are passed over as merely 

 normal proboscidiform animalcules or varieties of the same with their probosces 

 retracted. Mr. Hincks, on the contrary, favours the opinion that the two represent 

 adult and dimorphic conditions of the same form. The author's opinion concerning 

 this anomalous generic group, gained from a personal acquaintance with a variety 

 of species, combined with a study of the evidence adduced by the several 

 authorities already quoted, is that the non-proboscidiform or vermiform zooids must 

 be regarded as the larval or transitional condition of the fully developed zooids 

 provided with their characteristic probosces. It is clear from the testimony con- 

 tributed in all these instances, that the simpler vermiform zooids are produced by 

 gemmation from the proboscidiform ones, but never these latter from the former, 

 while the true internal embryos, corresponding with those of other typical Acineta, 

 are also forthcoming in a similar manner from the proboscis-bearing animalcules only. 

 Again, while frequently encountering these latter alone, or in isolated groups, 

 the vermifonn zooids appear almost invariably to occur only in companionship 

 with the proboscidiform ones, or as derivatives by gemmation from them. 



VOL. II. 2 C 



