752 
PROFESSOR WYVILLE THOMSON ON THE ECHINOIDEA OF THE 
PLATE LX. 
Cidaris affinis. 
Fig. 1. Full-sized specimen from off Cape Spartel. Natural size. 
Fig. 2. Apical aspect of test. X 2. 
Fig. 3. Portion of the test, showing the pore-arese. X 4. 
Fig. 4. One of the radials from the region of the ambitus. X 3. 
Fig. 4 a. A portion of a primary radiole, showing the sculpture. X 5. 
Fig. 5. Smaller spine from the neighbourhood of the mouth, x 2. 
Fig. 6. Spine from the border of an areola, x 6. 
Fig. 7. Dental pyramid. X 3. 
PLATE LXI. 
Porocidaris purpurata. 
Fig. 1. A mature specimen. Natural size. 
Fig. 2. The apical aspect of the denuded test. Natural size. 
Fig. 3. A portion of the oral aspect of the test. X 2. 
Fig. 4. Radiole from the region of the ambitus. Natural size. 
Figs. 5-7. Smaller radioles from different parts of the corona. 
Figs. 8-10. Paddle-shaped radioles from the neighbourhood of the mouth. Natural 
size. 
Fig. 11. Spine from the margin of an areola. X 3. 
PLATE LXII. 
Phormosoma placenta, Wy. T. 
Fig. 1. Oral surface of the test. Natural size. 
Fig. 2. Apical surface of the test. Natural size. 
Fig. 3. One of the smaller spines. X 50. 
Fig. 4. Portion of one of the larger spines. X 25. 
Fig. 5. Tridactyle pedicellaria. X 50. 
Fig. 6. Ophiocephalous pedicellaria. X 150. 
PLATE LXIII. 
Phormosoma placenta. 
Interior of the oral portion of the test, showing the peculiar character of that 
part of the test, the auriculae, the arrangement of the scales of the peristome, 
and the dental pyramid. X 2. 
A portion of the ventral surface of the test, seen from without, x 2. 
Fig. 1. 
Fig. 2. 
