Plate 3a. 



1-4. Podophora pedifera Agass. 

 From a specimen 74 mm. in diameter, including the spines. 



1. Tridentate pedicellaria. 3.9 mm. 



2. Ophicephalous pedicellaria. 2.9 mm. 



3. Triphyllous pedicellaria. 2.2 mm. 



4. Globiferous pedicellaria. 1.4 mm. 



t 

 5-8. Podophora atrata Agass. 



From a specimen 68 mm. in diameter, including the spines. 



5. Tridentate pedicellaria. 2.1 mm. 



6. Ophicephalous pedicellaria. 1.5 mm. 



7. Triphyllous pedicellaria. 1.2 mm. 



8. Globiferous pedicellaria. 1.4 mm. 



9-11. Colobocentrotus Mertensii Brandt. 

 From a specimen 72 mm. in diameter, including the spines. 



9. Tridentate pedicellaria. 2.7 mm. 



10. Ophicephalous pedicellaria. 1.9 mm. 



11. Triphyllous pedicellaria. 2.7 mm. 



All the figures are of relative sizes and under the same enlargement; the measurements 

 indicate the greatest length of the pedicellarise in the positions in which they are drawn. 



