22. 
23. 
24, 
24, 
25— 
2: 
26. 
27. 
28. 
MEM. M. C. Z., IX. No. 2.—ECHINODERMATA. 27 
Odd terminal tentacle, with the eye-speck (¢) of a young Asteracanthion about in the stage of fig. 18. 
Shows the process of resorption of the Brachiolaria into the young Starfish ; it commences at the anal extrem- 
ity, and in this case has gone on sufficiently far to leave the young Starfish riding upon the oral extremity 
of the Brachiolaria, which alone, with its brachiolarian and terminal arms, has retained its original shape 
and proportion. 
Bipinnaria asterigera. From Johannes Miiller, Ueber die Larven und die Metamorphose der Echinodermen, 
Zweite Abhandlung, (1848,) Pl. II. Abhandl. d. K. Akad. der Wiss. Berlin, 1849. 
A Bipinnaria, 1/' in size, seen from the ventral side: 1, upper arm (anal) ; 7, ventral arm (oral) ; 2, 3, 4, 5, 6, 
dorsal arms; a, mouth; 2, anus; d, dorsal vibratile cord ; dW, ventral vibratile cord ; ¢, a’, furrow 
between the vibratile cords of the arms. 
28. Asterias glacialis. From S. Lovén, Etudes sur les Echinoidées, 1874, Pl. LIT. Kongl. Svenska Vetens. 
Akad. Handl., XI, No. 7. 
Young Asterias, 1.3 mm., seen from the ventral side : a, b, ambulacral plates. : 
The same, seen from the abactinal side. In this stage the skeleton is almost exclusively made up of the api- 
cal and of the ambulacral system; a, dorsocentral plate (basal) ; b, interradial plates (genital) ; c, the 
terminal plates (ocular). The small plates () between the terminal and the angle of the interradial plates 
are the first dorsal arm-plates. 
Older specimen, 2mm., seen from the abactinal side ; the single plate (7) of the preceding figure is replaced 
by a set of three plates. Lettering as before. 
Another individual, 4.5mm., seen from the dorsal side ; one of the genital plates has been pierced by the 
madreporite (v) ; in each ray a pair of dorsal water-tubes (tr) have made their appearance. Lettering 
as for fig. 26. 
