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PLATE XI (continued).

Fig.
investment.
extremity.
35. Embryo of Plumatella fruticosa.

36. Statoblast of Lophopus crystallinus in a very early stage, in which it appears as a minute swelling upon the funiculus.

37. The same more advanced. The contents of the statoblast are here seen to be divided into two distinct portions.

A new bud is seen at each side within the cell, near its anterior

38. The same still further advanced. The division into two masses has disappeared, and the whole contents are surrounded by a distinctly cellular membrane.

39. The same after the appearance of the annulus, which as yet presents but a simply granular structure.

40. Peculiar cells from the annulus in a later stage of development.

41. The statoblast ruptured under compression, and the contents escaping in the form of minute cells. 41*. A group of cells constituting the contents of the statoblast, more highly magnified. 41°. Peculiar refractive corpuscles constituting the contents of these cells. 42. Statoblast of Plumatella repens, with the young polyzoon escaping from it. Its two faces have separated from one another, and are seen still adhering to the posterior part of the polyzoon which floats freely through the surrounding water. The

polypide is here represented as exserted from its cell. 43. The same, with the polypide retracted.

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