310 



PEOF. P. M. Duncan's eeyision of the 



Sismondia, 145. 

 Spatangidge, 216. 

 Spatagocystis, 286. 

 Spatangoida, 26, 166. 

 Spatangoidea, 25, 205. 

 Spatangomorpha, 243. 

 Spatangiis, 251. 

 Sphserechinus, 122. 

 Stegaster, 209, 210. 

 Stenonia, 216. 

 Stepbanocidaris, 27. 

 Stereosomata, 25. 

 Stigmatopygus, 182. 

 Stirechinus, 128. 

 Stomaforus, 255, 266. 

 Stomeehinus, 74, 

 Stomopneustes, 119. 

 Streptosomata, 25, 40. 

 Strongylocentrotus, 121. 

 Studeria, 185. 



Temnechinus, 108. 

 Temnocidaris, 33. 

 Temnopleuridffi, 96. 

 TemnopleuriiiEe, 97, 106. 

 Temnopleurus, 106. 

 Tetracidaris, 35. 

 Tetragramma, 60. 

 Thegaster, 294, 305. 



Thylechinus, 89. 

 Tiarechinus, 19. 

 Tiaris, 49. 

 Toxaster, 219. 

 Toxohrissus, 248. 

 Toxocidaris, 121. 

 Toxopneustes, 121, 130, 131. 

 Trachyaster, 228, 229. 

 Trachypatagus, 255. 

 Trematopygus, 175. 

 Trichodiadema, 61. 

 Trigonocidaris, 105. 

 Tripneustes, 132. 

 Tripylus, 226, 227, 229, 231. 

 Trochalia, 181. 

 Troschelia, 244. 

 Tuberaster, 222, 260, 263. 

 Typhlechinus, 13. 



Urechininae, 211. 

 Urechiaus, 212. 



VerbeeJcia, 248. 



Xanthobrissus, 246. 

 Xenocidaris, 293. 



Zeuglopleurus, 103. 



ADDENDA ET COEEIGENDA. 



Phoemosoma, p. 42. Prof. Jeffrey Bell has shown (Ann. & 

 Mag. Nat. Hist. 1889, ser. 6, vol. iv. p. 436), during the printing 

 of this Eevision, tliat in PJiormosoma placenta, "Wyv. Thorns., the 

 internal branchiae, or " Stewart's organs," may be present in a 

 rudimentary or vestigial condition. He observes tbat the organs 

 are not to be traced in P. lursarium and P. tenue ; but he does 

 not lay mucb stress upon this, as tbe specimens, unlike those of 

 Phormosoma placenta, had been for many years in spirit. The 

 longitudinal internal muscles, so well described by Drs. Sarasin in 

 Astheiiosoma, are absent in Phormosoma. It is difficult to make 

 out whether the indications of the presence of the organs, in 

 the drawing given by A. Agassiz of P. tenue, ' Challenger ' 

 Report, pi. xiv. fig. 2, are really not intestinal. This appears to 

 be the case in pi. xii. fig. 2. 



