Bd VI: 4) THE ECHINOIDEA. 1 1 1 
Fig. 17. Valve of small globiferous pedicellaria of Austrocidaris canaliculata , from the 
inside. 7 %. 
» 18. Abactinal radiole of Austrocidaris canaliculata. 6-5 / t . 
Fig. i. 
» 2. 
» 3* 
» 4. 
» 5 - 
» 6. 
» 7. 
» 8 . 
» 9. 
» ro. 
» ii. 
» 12. 
» 13. 
» 14. 
» 15. 
Plate XV. 
Part of ambulacrum of Arbacia crassispina. 8 /i. 
Valve of triphyllous pedicellaria of Arbacia Dicfresnii. I75 /i. 
Part of ambulacrum of Arbacia Dufresnii. s/i. 
The point of an actinal spine of Arbacia crassispina. I 5 /i. 
Valve of ophicephalous 
pedicellaria of Arbacia 
crassispina. 
7 %. 
» » » 
» » » 
Dufresnii. 
7 %. 
» » » 
» » » 
crassispina. 
7 % 
The point of an actinal spine of Arbacia Dufresnii. I5 /i. 
Ocular plate of Arbacia Dufresnii. I */i. 
Stalk of ophicephalous pedicellaria of Arbacia Dufresnii. IZ5 /t. 
Ocular plate of Arbacia crassispina. I4 /i. 
Ambulacral plates of Tetrapygus niger. IO /i. 
Valve of tridentate pedicellaria of Arbacia Dufresnii. s %. 
» » » » » » crassispina. 7 %. 
Ambulacral plates of Tetrapygus niger. IO /i. 
Fig. i. 
2. 
» 3 - 
» 4. 
» 5- 
» 6 . 
» 7. 
» 8. 
9 - 
» i 
o. 
1 1 . 
» 12. 
» 13. 
i5- 
16. 
Plate XVI. 
Tridentate pedicellaria of Sterechinus Agassizii. 5 %. 
Valve of tridentate pedicellaria of Loxechinus albus. 65 j%. 
Globiferous pedicellaria, small form, of Notechinus magellanicus (comp. Fig. 19). s %- 
Sphæridia of Loxechinus albus. 170 f. 
Tridentate pedicellaria of Loxechinus albus. 5 °/i. 
The point of a secondary spine of N otechinus magellanicus. 50 f. 
» » » » » » » Sterechinus Agassizii. 5 °/i. 
Group of spicules from tubefoot » » » z25 /i. 
Spicules from tubefoot of Notechinus magellanicus ; a. fully developed, b. develop- 
mental stage. Z25 ,/i. 
Abnormal, two-headed triphyllous pedicellaria of Notechinus magellanicus ; the left 
head slightly restored. 7 %. 
Secondary spine of young Notechinus magellanicus. 5 %. 
Primary » » » » » 5 %. 
Outer part of secondary spine, with the point regenerated, of Sterechinus Agassi- 
zii. 5%. 
Valve of ophicephalous pedicellaria of Loxechinus albus. 6s /j. 
Globiferous pedicellaria of Sterechinus Agassizii. 
Valve of triphyllous pedicellaria of Loxechinus albus. I7 %. 
