200 CEYLON PEARL OYSTER REPORT. 



EXPLANATION OF PLATES. 



PLATE I. Polypus herdmam, n. sp. 

 Fig. 1. Dorsal view of the type specimen. Natural size. 



PLATE II. 

 Fig. 1. Polypus A. Natural size. 



2 C 



3. G. The second arm on the left side, to show the double row of chromatophores. x 6 

 diameters. 



4. ,, B. Natural size. 



5. C. Ventral surface to show the rows of chromatophores parallel with the margin of the 



mantle. x 5 diameters. 



6. F. ,, arrangement of the large chromatophores on the ventral 



surface. x 5 diameters. 



7. J. Two specimens, x 2 diameters. 



8. arborescens, n. sp., one of the medium sized branched papilla;, x 43 diameters. 



9. ,, ,, larger branched papilla;, x 43 diameters. 



10. aculeatus, tip of the hectocotylised arm of specimen 266. x 2-A diameters. 



11. D. Ventral surface to show the patch of large chromatophores. x 3 diameters. 



12. ,, arborescens, n. sp., specimens in various attitudes to show the branched papillae. Nat. size. 



13. ,, aculeatus, specimens showing the characteristic surface markings. Natural size. 

 Figs. 1, 2, 4, 7, 12 and 13 are from photographs. 



PLATE III. Papillae of Polypus arborescens, n. sp. 



Fig. 1. Section near the base of a papilla. x 38. 

 ,, 2. ,, somewhat higher up. x 38. 



,, 3. taken where the lateral branches begin, x 38. 



,, 4. A portion of a section such as fig. 1, extending from the central mass to the outside. x 286. 



5. Section through a branch, showing a large amount of granular material. x 250. 



,, 6. Longitudinal section of one of the thicker branches. x 250. 



,, 7. Section through one of the thinner branches. x 286. 

 8. ,, close to the tip of one of the branches, x 286. 



9. Diagrammatic vertical section of one of these organs. x 286. 



,, 10. Section at right angle to the surface through one of the epithelial organs. x 430. 



,, 11. 01 ilique section, showing the nucleus. x 430. 



12. Horizontal section, taken at the level A, B in fig. 9, showing the central plug, with layer of 



epithelial cells and connective-tissue around this again. x 430. 



,,13. A similar section, taken somewhat lower down, at the level of O, 1>, fig. 9. x 430. 



Explanation of Letters. 



J., bundles of fibres parallel to axis of papilla. 



bl., blood vessels. 



c, connective-tissue. 



ch., chromatophores. 



cm., central mass. 



ep., epithelium. 



/., bunch of fibrils, radiating from the surface of the , organs. 



epithelial organs. '., radiating connective-tissue fibres 



g., granular tissue. 



/., lacunae. 



in., mass of granular tissue in epithelial organs. 



n., nuclei. 



m:, organs in the epithelium. 



p., central plug of granular material in epithelial 



