MUSEUM OF COMPARATIVE ZOOLOGY. 149 
rw. Right water-vessel, hydroceel. 
sp. Spine of arm. 
spl. Spoon-shaped plate. 
t 
Teeth. 
if. Unpaired or terminal feeler. See wt. 
to. Torus angularis, jaw-plate. 
tp. Terminal plate, terminal. 
U. Connection of pentagonal larva with parent. In stages earlier than 
pentagonal larva also found. 
v. Ventral plate, lower arm-plate. 
wt. Terminal end of water-vessel of the arm. 
PLATE I. 
Figures drawn with Camera lucida, Obj. BB. 
Fig. 1. Pluteus of Ophiopholis aculeata, Gray, in a little older condition than that 
figured in Fig. 23, Pl. I., Bull. Mus. Comp. Zoil., Vol. XII. No. 4. 
** 2. The same somewhat older. Seen from side on which mouth opens. 
“ 3, Adult pluteus of 0. acwleata before young Ophiuran has begun to form. 
The drawings from which these figures were made are from plutei taken at Frye’s 
Island, New Brunswick. This island bears the name of Cailiff’s Island on the Admi- 
ralty Chart. 
The same plutei are common at Eastport, Maine. 
PLATE II. 
Figures drawn with Camera, Objs. BB, DD, Zeiss. All except Fig. 1 with Obj. BB. 
Fig. 1. Blastosphere of Amphiura squamata. Diameter, .15 mm. 
‘¢ 2. Same, younger. 
Gastrula. 
Ventral view of a bisymmetrical larva, unattached. 
The same, lateral view, attached. 
Somewhat older larva than the last, showing the vasoperitoneal sacs or 
water-tubes. 
The last, lateral view, unattached. The remnant of the attachment in the 
upper right-hand corner. 
‘© 8. An older larva than the last, attached. Dorsal view. 
“* 9. The same, older. 
‘©10. The same, still older. 
“*11. Somewhat older larva. 
**12. A pentagonal attached larva with well-formed radial, dorsocentral, and 
terminal plates. Abactinal view. Attachment at w. 
**13, Youngest free Amphiura, unattached to parent. Found free in mother. 
Abactinal view. The great prominehce of two of the terminal plates, tp, 
is due to the position which the specimen had when drawn. 
FR 
“T 
