Prof. H. Karsten on Rhynchoprion penetrans. 293 Fig. 11. Acineta tuberosa, Ebr., embryo of, showing, in series, the changes which it undergoes from the active state on its exit from the parent, to its passive, tentaculated, and spherical form : a, active state on issuing from the parent, when it is provided with a circlet of vibratile cilia ; b, its globular form, assumed on becoming com-paratively passive and stationary, -r^Virth of an inch in diameter, the cilia passive and curved from the centripetal force occasioned by the rotatory motion which they originally communicated to the young Acineta in its active state; c, the cilia regaining their straightness, and becoming shorter ; d, the cilia disappearing, and short tentacles projected; e, the cilia gone and the tentacles increased in number and elongated. India, fresh water. Fig. 12. Collodictyon triciliatum, n. sp. Length y-iT-st of an inch : a, pos-terior (?) view, showing bifid extremity, three cilia, central line and nucleus, cellular structure and granules ; b, lateral view ; c, presenting a digestive space containing an incepted ProtO' coccus in the 8-cell division; d, ditto containing a Crumenula texta nearly as large as itself; e, outline of another but common, form of this Rhizopod ; /, ditto of a globular form ; g, one en-closing the central portion of a filament of Oscillatoria, while the two ends are outside the animalcule ; h, length on the same scale as the Actinophryans ; i, length on the same scale as that of the testaceous Rhizopoda, figs. 13 6? and 14 g. India, fresh water. Fig. 13. EuglypJia spinosa, n. sp. ; specimen T-fT-st of an inch long and •jj-l-g^th of an inch broad ; animal retracted within a diaphragm, and passive : a, view of broad side of test ; a', ditto of narrow side, or lateral view ; b, scales on test ; c c c c, moveable spines on fixed tubercles ; c', more magnified view of the spine ; d, dotted out-line of test on a scale of ^-th to ^ai^th of an inch, for comparison, with other figures of testaceous Rhizopoda, I. c. ; e, diaphragm; f, portion of sarcode containing fragments of food ; g, ditto charged with granules ; h, nucleus. England, fresh water. Fig. 14. Euglypha globosa, n. sp. ; specimens 3^^th of an inch in diameter: a, empty test covered with circular scales hexagonally arranged, also showing the broad side of the neck and open aperture; b, ditto, showing the narrow side (or lateral view) of the neck and closed aperture, also c c, supernumerary scales ; d, test contain-ing the animal, passive, with closed aperture ; e, sarcode contain-ing fragments of food ; /, nucleus in posterior and granular por-tion of sarcode. England, fresh water. XXXIII. — Contribution towards the Knowledge of the Rhyncho-prion penetrans. By Hermann Karsten*. [Plates VIII. & IX.] [In this paper Professor Karsten remarks upon the imperfect knowledge which we still possess of this curious parasite — the Nigua^ Chigoe, Jigger, or Sand-Flea of tropical America, — not-withstanding that the first European visitors to the New World * Translated from a separate copy of the paper in the ' Bulletin ' of the Society of Naturalists of Moscow, communicated by the author.
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