Narrative of the Voyage of H.M.S. Rattlesnake, Commanded By the Late Captain Owen Stanley, R.N., F.R.S. Etc. During the Years 1846-1850. — Volume 1 / Including Discoveries and Surveys in New Guinea, the Louisiade Archipelago, Etc. to Which Is Added the Account of Mr. E.B. Kennedy's Expedition for the Exploration of the Cape York Peninsula. By John Macgillivray, F.R.G.S. Naturalist to the Expedition.

by John MacGillivray

Habitat: Bass Strait, 45 fathoms.

The cells in this species are small, inflated or ventricose, and as it were sub-globular above, becoming much attenuated below--but the cavity of the cell does not appear to extend into this contracted portion, in which is contained the connecting tube strengthened by calcareous matter--the inferior continuation of the lateral alae, which descend from the base of the avicularium. Owing to the large size of the avicularia, the upper part of the cell is much widened, and the whole acquires somewhat of a triangular form, and has a peculiar rugose aspect, derived, in part also, from the large size and elevation of the acuminated papillae, not only of the vittae but on the surface of the cell itself. The central umbo or crest posteriorly is a marked feature.

c. Without vittae or fenestrae.

13. C. carinata, n. sp.

Cells oval, narrowed at both ends; lateral processes (without avicularia ?) projecting horizontally upwards from the sides of the mouth about the middle of the cell. Mouth nearly central, with a small tooth on each side, and below it a triangular space with three strong conical eminences. The cell which bears the ovicell geminate.

Habitat: Bass Strait, 45 fathoms.

This remarkable form differs so widely in many respects from any of its congeners, as almost to deserve to be considered as the type of a distinct sub-genus. The lateral processes, which may be taken to represent the perfect avicularia of the other species, are, as far as can be ascertained from specimens that have been dried, without a movable mandible, and are probably really so, because there is no corresponding beak. These processes are channelled in front, nearly from the base to the extremity; they arise by a broad base on each side of the mouth, and on the front of the cell, and from the conjoined bases is continued upwards and downwards, or to the top and bottom of the cell, a prominent flattened band. The expanded bases circumscribe an oval space, nearly in the centre of the front of the cell, the upper two-thirds of which space are occupied by the circular mouth, on each side of which is a small calcareous tooth, to which apparently are articulated the horns of the semilunar lateral cartilage. The lower third is filled up by a yellow, horny (?) membrane, upon which are placed three conical eminences, disposed in a triangular manner. The back of the cell is very convex, and has running along the middle of it an elevated crest or keel, which is acuminate in the middle. The ovicell is situated in front of the cell below the mouth, and below it are three considerable-sized areolated spots, disposed, like the three conical spines, in a triangle. The cells upon which the ovicells are placed are always geminate, that is to say, have a smaller cell growing out from one side.

6. Calpidium, n. gen. Table 1 figures 3 to 5.

Character: Cells with an avicularium on each side; with two or three distinct mouths, arising one from the upper part of another, in a linear series, all facing the same way, and forming dichotomously-divided branches; cells at the bifurcation single; ovicells ---- ?

This very peculiar genus, remarkable as it is, seems hitherto to have escaped notice. It is distinguishable from Catenicella, in the first place, by the anomalous circumstance that each cell is furnished with two or more, usually three, distinct keyhole-shaped mouths, and is doubtless inhabited by three distinct individuals. Whether these are separated from each other by internal partitions is unknown, but the closest examination of cells rendered transparent by means of acid fails to discover such. In cells thus prepared, there are apparent, however, three distinct masses, reaching from the bottom of the cell to each orifice, and which are probably the remains either of the body or of the retractor muscles of the animals. Another point of difference from Catenicella is the non-gemination of the cell at the dichotomy of a branch. The avicularia, moreover, do not form lateral projections, but are sessile, or imbedded, as it were, in the sides of the cell immediately below the upper angles.