REPOET ON THE ECHINOIDEA. 289 



Fig. 6. Ambulacral and interambulacral plates of abactinal surface of same specimen 

 near^ambitus (^-5-). 

 „ 7. Ambulacral and interambulacral plates of actinal surface of same near 

 ambitus (i^). 



Fhoi^mosoma tenue, A. Ag. (fig. 8), p. 91. 

 „ 8. Abactinal system of specimen measm-ing 127 mm, (f). 



PLATE XVIII. 



Asthenosomcc pellucidnm, A. Ag. (figs. 1-6), p. 85. 



Fig. 1. Segment of test of specimen from tlie actinal side, measuring 37 mm. in 

 diameter (f ). 



„ 2. Same, seen from the abactinal side. 



■ „ 3. Abactinal system of same (f). 



„ 4. Segment of test of specimen measuring 59 mm., seen from the actinal side (f ). 



,, 5. Same, seen from the abactinal side. 



,, 6. Abactinal system of same (f ). 



Phormosoma tenue, A. Ag. (figs. 7-9), p. 91. 



,, 7. Segment of test of specimen measuring 90 mm., seen from the abactinal side (f). 

 „ 8. Same, seen from the actinal side. 

 „ 9. Abactinal system of same (J). 



PLATE XVIIP. 



Phormosoma tenue, A. Ag. (figs. 1-13), p. 91. 



Fig. 1. Portion of test of specimen, measuring 145 mm., adjoining ambitus of abactinal 



surface (i^). 

 ,, 2. Denuded portion of test of abactinal surface of same, near abactinal system. 

 ,, 3. Denuded portion of actinal surface of test of same, near ambitus. 

 ,, 4. Interior view of preparation of abactinal surface, showing subdivisions of coronal 



plates; specimen measuring 131 mm. (f). 

 ,, 5. Interior view of actinal surface, not cleaned (f ). 

 „ 6. Main amljulacral tube, with lateral branches leading to ampuUse, actinal 



surface (|~). 

 ,, 7. Interior view of abactinal part of test, median part (f ). 

 ,, 8. Interior view of abactinal part of test, preparation (f). 

 ,, 9. Actinal part of test, median part (f ). 



(ZOOL. CHALL. EXP. — PART IX 1881.) I 37 



