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. 



