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. 



