BIOLOGY. II, B. 
Ech. 19 
(ii) Variation. 
(a) In form : — Of Sphcerothuria ; Ludwig (70) p. 142 : of Echino- 
cyamus elegans and Laganum delicatum; Mazzetti (78) pp. 240 & 241. — 
In size of Strongylocentrotus lividus , smallness due to competition ■with 
Sphcerechinus (p. 419), in size and colour, between littoral and deep- 
water forms of Asterias glacialis (p. 407), Echinaster sepositus (p. 408) ; 
Koehler (56). 
(b) In form and surface characters : — Size, spines, marginals, form, 
&c., in Bentliopcctcn spinosus (p. 246), Plutonaster agassizi (p. 248), 
Pseudarchasier intermedius (p. 249), Leptopty chaster arcticus (p. 255), 
Isaster bairdi (p.261), Ophioglypha saurura (p. 289), 0 . tessellata (p. 292), 
0. bultata (p. 295) ; Verrill (125). — Number of jaws in pedicellarire, 
Borocidaris papillata and others; Bateson (6) p. 429: (see also 
II, B, ii, d, 2). In surface characters of Ophiothrix ; Bell (7) p. 407. — 
Marginals of Rhegaster ; Pfeffer (93) p. 102. — Spines absent from 
infero-marginals of Archaster typicus young ; Bell (7) p. 402. — In 
spines on marginals, Astropecten sqaamatus ; Koehler (56) p. 410. — 
Of Ophioglypha albida in directions of O. affinis and 0 . grubci , buccal 
shields, &c. ; Koehler (56) p. 413. — Modifications in large individuals of 
Cyphosoma maresi ; Gauthier (37) p. 22. 
(c) In colour : — Abnormally coloured Ophioglypha albida (p. 331), 
colour variations of radial shields in Ophiothrix fragilis (p. 336), black 
Asterias rubens (p. 339); Meissner & Collin (80): (see also 
II, B, ii, a). 
(d) Meristic variation :— (1) Variation from pentamerous symmetry, — • 
Previously recorded cases collected and discussed, also Asterias with 
8, 4, and 6 rays, Asterina with 4 and 6,' Porania with 4, Cribrclla with a 
branched arm ; Bateson (6) pp. 432-447. — Four-rayed Benthopecten 
spinosus (p. 246), Dytaster grandis (p. 248) ; Verrill (125) : Asterias 
rubens; Meissner & Collin (80) p. 338. — Four- and Six-rayed Galerites ; 
Laur (61) p. 6. — Six-rayed : Isaster bairdii (p. 262), Odontaster liispidus 
(p. 264) ; Verrill (125) : Stichaster ; Pfeffer (94) p. 98. 
(2) Reduplication or absence of parts, — In brachials of Critioidea, cases 
quoted and discussed ; Bateson (6) p. 421 : in number of marginals in 
Astropecten irregularis ; Meissner & Collin (80) p. 337 : in arrange- 
ment of syzygies of Antedon bassctt-smithi ; Bell (7) p. 399. — Doubling 
of posterior ambulacrum in Cardiaster ; Gauthier (37) p. 36. — Divided 
ray in Uraster rubens ; Winckworth (129). — Pedicellarim minus one 
half, in Pararchaster ; Perrier (92) p. 258 : (see also II, B, ii, b). 
(e) Abnormalities : — Budding of supplementary ray in Benlhopecten 
spinosus ; Verrill (125) p. 246. — Abnormal arrangement of mesenteries 
in Benthodytes ; Ludwig (70) p. 58. — Asymmetrical Brissopsis lyrifera , 
with prominent posterior ambulacra ; Meissner & Collin (80) p. 344. 
— Unusual development of right hydrocoele in larva of Asterina ; 
Macbride (74). 
