ERRATA. 
Page 307, line 23, for cavaluted, read convoluted. 
Page 310, line 8, page 401, line 12,and elsewhere, for Osfrwa, read Ostrea. 
Page 383, line 23, for Molidia, read Montagua. 
Page 383, line 26, for Cavolina, read Coryphella. 
Page 392, line 23, for micropthalma, read microphthalma. 
Page 393, last line, for Sargatia, read Sagartia. 
Page 399, line 21, for Leptochiton, read Chetopleura. 
Page 399, line 32, for Leptochilon, read Trachydermon. 
Page 405, line 27, for Pucrate, read Eucratea, 
Page 407, line 38, for reproducsive, read reproductive. 
Page 415 line 25, for Unicola, read Unciola. 
Page 427, line 15, and page 429, line 28, for Melitta testudinaria, read Mellita pentapora. 
Page 433, line 34, for Amphipholis, read Amphiura. 
Page 444, line 12, for tidentata, read tridentata. 
Page 457, line 39, for Pandaru, read Pandarus. 
Page 459, line 36, for Echthrogalus, read Echthrogaleus. 
Page 487, line 10, for A. planaria,read A Planaria. 
Page 4858, line 4, for cantenula, read catenula. 
Page 496, line 28, for 4. ternata,read C. ternata. 
Page 498, line 5, for Tedania, read Halichondria panicea. 
Page 498, line 30, for Augustus, read angustus. 
Page 504, line 41, for page 433, read 432. 
Page 508, line 5, for Acutum,read A. acutum. 
Page 509, line 18, for laevigata, read discors. 
Page 509, line 32, for thraci-formis, read thraciformis. 
Page 509, line 33, for Simpson, read Stimpson. 
Page 547, line 15, for Panopius, read Panopeus. 
Page 561, line 43, for pingus, read pinguis. 
Page 619, line 16, for Cosco, read Casco. 
Page 619, last line, for Cisco, read Casco. 
Page 640, first line, for fig. 127, read fig. 124, 
Page 666, line 15, after Montagua pilata, insert Plate XXV, fig, 124, 
Page 680, line 18, for 185, B., read 184, B, 
Page 695, line 34, for fig. 238, read 243. 
Page 716, line 35, for fig. 368, read 268, 
