34 Ed tin. 
XIV. ECHINODERMA. 
ii. Relations of Echinoderma :—Gegenbaur (97) p. 64.—Deri¬ 
vation of Dipleurula ancestor from Coelentera , and its transformation 
into the primitive Pelmatozoon ; Bather (14a) p. 621. — The bilateral 
ancestor as indicated by larva of Cribrella ; Masterman (195) p. 402.— 
Grin, are oldest Echinoderms (diagram of “ Urcrinoid,”) and are de¬ 
scended from Gnidaria , apparently by direct evolution from Alcyonaria : 
other Echinoderms derived from them by loss of stem and the 
consequent locomobility, diagram of a Holothurian; Schneider (255) 
pp. 212-217. 
iii. Phytogenies of smaller groups :—Evolution of the various 
classes from a lived ancestor; Bather (14a) p. 622.—-Origin of 
Asteroidea from a Dipleurula through a fixed form, and relations to 
other classes ; Masterman (195) p. 408.—Origin of classes, Cystidea 
gave rise to Hoi. and Grin., and Grin, to Blast : origin of the remaining 
classes uncertain, but Ech. derived from Oph. ; Russo (245) p. 67 et sqq. 
Phylogeny of Melocrinidae , Taxocrinidae , “ Comatulidae ” Hybo- 
crinidae , Heterocrimdae , and other forms enumerated under a, i ; 
Jaekel (134).—Evolution of Chalk Ech ., esp. Micraster , Echinocorys , 
Rhynchopygus ; Grossouvre (116) pp. 16-22. 
(B.) MORPHOLOGY. 
i. Anatomy:— 
a. ECHINODERMA. 
1 . General accountspopular; McHenry & Watts (184) 
p. 99.—Of fossils; Cole (49) pp. 375-389.—Analysis of Echino- 
derm characters; Bather (14a) p. 623.—See also n, e, i, d. 
2 . S y m m e t r i e s :—Vacant. 
3. Homologies of Classes:—with special reference to fossils; 
ViNASSA de Regny (288) pp. 247-252.— Theories of Echinoderm 
morphology discussed, especially the calycinal, the pentactaea, 
and the pelmatozoic, the last being advocated : relations of the 
classes; Bather (14a) p. 618.—Homologies of coeloms in the 
classes, as inferred from larval development; Masterman (195) 
p. 408.—Homologies of genital cords and associated sinuses 
and lacunae, of radial intestinal absorbents, ovoid gland, &c. in 
the classes of living Echinoderms; Russo (245) p. 59.—Homo¬ 
logies of body-wall: Hoi. compared with Ech., Ast., & Oph. : in 
all it consists of 3 layers, outer and inner forming stereom, 
middle one containing lacunae derived from schizocoel; He- 
rouard (126). 
4 - Skeletal tissue or Stereom:—relations to perisome; Gegen¬ 
baur (97) pp. 80, 182.—Spicules and plates of Echinoderms 
considered as crystal individuals, resume of literature; Bieder- 
mann (23) pp. 160-170.—Law of formation of plates: size of 
mesh decreases with order of formation: shapes due to laws 
of crystallisation acting in a living medium; Herouard (125). 
Recent and fossil Ech. stereom proved calcite not aragonite 
by chemical tests; Meigen (200). 
5. Skeletal Anatomy:—The skeleton is morphologically ex¬ 
ternal in part, and internal in part (see a, 3 ), ambulacrals of 
Ast. are internal, of Ech. external; Herouard (126). 
6 HjMrocoel and associated cavities:—Vacant. 
7. Coelom and other Body-cavities, and their Contents:— 
Various lacunae and sinuses, their origin, relations in adult, 
and homologies ; Russo (245). 
