32 Mr. L. Barrett on two new species of Ecliinodermata. Fig. 4. Ditto, with second root-cell and rootlet-cell formed (lateral view) : {d) primary nucleus received into the dilatation of the cell-wall, d', and rendered stationary ; {g) ohlique, sigmoid septum ; [h) root-let-cell ; {k) secondary nucleus, elongated, presenting the hya-line vacuole in plurality; (/) nucleus of rootlet-cell. The re-maining fixed protoplasm of the first root-cell having now been broken down by the vacuoles, circulates freely, with the rotating protoplasm, over the septum of the second root-cell and that of the rootlet-cell. Fig. 5. Ditto, ditto, with first or duplicating septum of rootlet-cell formed, and multiple division of primary nucleolus (direct view) : {d) pri-mary nucleus with nucleolus divided into smaller nucleoli ; (m) vacuoles beginning to break down fixed protoplasm in the lower part of second root-cell ; {n) septum duplicating rootlet-cell ; (o, o) nuclei of rootlet-cells ; {p) lower extremity of second root-cell which is partly behind rootlet-cell. Fig. 6. Ditto, ditto, with rootlet-cell quadrisected, and primary nucleus become effete (direct view) : (a) effete nucleus from which the small nucleoli have disappeared; {q, q, q, q) nuclei of rootlet-cells; [s] second septum of rootlet-cell; {t) lower part of fixed protoplasm in second root-cell broken down and become rotatory. This cell is now brought into the state of figure 2. F^g. 7. More magnified view of primary nucleus when young, 1 -300th of an inch in diameter : («) nuclear utricle ; (6) mucus occupying its interior ; (c) nucleolus ; (d) hyaline vacuole. Fig. 8. Ditto of primary nucleus when old ; hyaUne vacuole in plurality. Fig. 9. Secondary nucleus soon after becoming visible ; presenting double nucleoli. Fig. 10. Ditto, some time after this, with nucleoli united. The next stage is represented in fig. 7 and so on. I^g. 11. Nucleus with double nucleoli, presenting a transparent ring round them respectively, indicative of the presence of a capsule. FHg. 12. Lateral view of primary nucleus after having become stationary, presenting (a) vacuoles in its interior. Fig. 13. Elongated sac-like form of primary nucleus after having become stationary; presenting small nucleoli also elongated (a, a, a). This sac, which is a frequent termination of the nuclear utricle, is sometimes very long, and more or less irregular in form than the figure. Fig. 14. Globular cells connected with the "irregularly shaped bodies" (e, e) ; sometimes seen without the latter : (a) common form of this " body." Fig. 15. " Granules" much magnified : (a) round, elliptical, greenish; (b) angular, colourless. III. — On two species o/Echinodermata new to the Fauna of Great Britain. By L. Barrett, F.G.S. [With a Plate.] The two following species are interesting additions to our fauna, made by Mr. M'Andrew. The Amphidotus agrees with the brief description of A. gibbosuSy Agass., in the Ann. Sc. Nat. t. viii. p. 11 : the Comatula is new.
BioStor
