ERRATA.
Page 23, line 3 from top, add "Compare also Myxobrachia cienkowski, Wagner, 1872, L. N. 23."
Page 40, bottom line, add "The two following species are incompletely known:—Sphœrozoum orientale, Dana, 1863, Ann. and Mag. Nat. Hist., vol. xii. p. 54. Sphœrozoum sanderi, Dœnitz, 1871, L. N. 60, p. 71."
Page 65, line 15 from top, add "Cenosphœra radiata, Zittel, 1876 (L. N. 29, p. 84, Taf. ii. figs. 7, 8), a fossil Cretaceous species, is closely allied to Cenosphœra compacta."
Page 84, line 17 from top, add "Caryosphæra polysphærica, Bütschli, 1882 (L. N. 41, Taf. xxiii. fig. 12) is probably a Cromyosphæra (fossil in Barbados)." Page 95, line 11 from top, add "Dermatosphæra, Ehrenberg, is a Collosphæra with small pores (compare L. N. 16, p. 533)." Page 97, line 8 from foot, for "xxiv." read "xxxiv." Page 122, line 14 from foot, for "Spongolonche" read " Spongolonchis." Page 149, lines 1, 4, 6 and 12 from top, for " Spongolonche" read "Spongolonchis." Page 149, line 2 from foot, for "Spongolonche" read" Spongolonchis (oróyyos, Xoyxis)." Page 172, line 4 from foot, add Synonym "? Haliphormis hecacantha, Ehrenberg, 1872, L. N. 24, Taf. x. fig. 6." Page 216, line 11 from foot, add "Taf. xiii." Page 308, line 4 from top, add "Compare Haliomma oblongum, Harting, 1863, L. N. 18, p. 15, pl. 2, fig. 42. Page 326, line 14 from foot, for "1872" read "1875." Page 461, line 12 from foot, delete "H." Page 463, line 10 from top, add "Indian Ocean, Cocos Islands, Rabbe." Page 492, bottom line, add "Porodiscus haeckelii = Trematodiscus haeckelii, Bütschli, 1882, L. N. 41, Taf. xxiv. figs. 5a, 5b." Page 509, bottom line, add "Stylodictya haeckelii, Zittel, 1876, L. N. 29, p. 85, Taf. ii. fig. 9, is a fossil Cretaceous species, related to Stylodictya multispina." Page 534, line 11 from foot, add "Indian Ocean, Cocos Islands (Rabbe). Also in the Central Pacific, Station 267." Page 584, line 12 from top, for "1872" read "1875." Page 586, line 7 from foot, add " Spongotrochus ehrenbergii, Bütschli, 1882, L. N. 41, Taf. xxvi. figs. 1a, 1b." Page 633, bottom line, add "Monozonium hartingii = Haliomma amphiaspis, Harting, 1863 (L. N. 18, p. 15, pl. 2, fig. 43)."
