366 



microscopic wheels. In C. Icevis these wheels are very minute and 

 clustered in little groups beneath the epidermis, and when the sur- 

 face is raised with a needle point they are set free. In Chiridota 

 violacea, figured by Midler in the Berlin Transactions, and again in 

 Dr. Carpenter's ' Microscope,' the wheels are attached to a common 

 connecting thread. 



Prof. Steenstrup has formed a genus (or subgenus) for another 

 Greenland species — Myriotrochus Rinkii (figs. 27-31), in wbich 

 the wheels are larger and scattered over the skin, each having its 

 own stalk. These wheels first appear as little stars, with rays or 

 spokes of various number (18 to 25), which increase until they 

 attain their normal length, and then expand at their ends until they 

 join and form a rim (or tire) to the wheel. A ring of spines is 

 afterwards formed on the thickened margin ; the spines are pointed 

 towards the centre of the wheel, and are as numerous as, or rather 

 more numerous than, the spokes. As the wheels only occur on the 

 three dorsal inter-muscular bands, they can scarcely assist in locomo- 

 tion, and must be regarded as ornamental characteristics, such as 

 nature loves to bestow for us to marvel at. 



Synapta, Eschscholtz, 1829. 



1. S. vittata {Fistularia), Forskal, 1775. Suez, Red Sea. 



2. £. reciprocans, Forsk. Suez, Red Sea. 



3. S. inhcerens {Holothuria), O. F. Midler, 1781 ( = Holothuria 

 flava, Rathke ; Jemania Henslowana, Leach ; Synapta Duverncea, 

 Quatr.). Christiansand og Kragerb'e ; Aberystwith and Criccieth, 

 North Wales {H endow and Wilton) ; Falmouth, Cornwall {W. P. 

 Cocks) ; Bantry, W. Ireland (MacAndrew and Barrett) ; Guernsey 

 (E. C. Buckland) ; lies Chaussey, near St Malo (Quatr ef ages). 



4. <S. digitata {Holothuria), Montagu. Devonshire {Mont., 

 Cranch, Alder, Kingsley) ; Falmouth {Mr. Cocks) ; W. Ireland {Mr. 

 Barlee) ; Rothesay, Bute {Mr. Alder) ; Vigo Bay, N. Spain {Mac 

 Andrew) ; Trieste {Joh. Miiller, Dr. Hartmann). 



5. S. mamillosa, Esch. Tahiti. 



6. &. maculata, Chamisso & Eysenh., Act. Nat. Cur. x. p. 1. 1. 25. 



7. S. ? verrucosa {Chiridota), Esch. Sitcha, Russian America. 



8. S. Beselii, Jiiger, 1833. Celebes. Berlin Trans, t. 6. f. 15. 



9. S. radiosa, Reynaud (teste Jager). Coromandel. 



10. S. 6identata,W. & B. 1858. China. 



11. 8. lappa, Midi. Berlin Trans. 1854, t. 6. f. 1 6. W. Indies. 



12. £. serpentina, Midi. Id. f. 17. Celebes. 



Chiridota, Esch. 



Icevis {Holothuria), O. Fabr. Greenland, 

 violacea, Peters. Mozambique. 

 ? purpurea, Less. Falkland Islands. 

 Ivmbricus, Esch. I. Radak, Coral Sea. 

 discolor, Esch. Sitcha, Russian America. 



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