xviii

FIGURE

LIST OF ILLUSTRATIONS.

pigmented epithelium; d, the lining epithelium of the mantle;
e, the lens; f, the ligament supporting the lens; g, the
retina; h, the tapetum; k, the pigment; m, the retinal
nerve; n, complementary nerve

98. Schematic representation of the soft and some of the hard parts in a shell of a Chiton (Acanthopleura), as seen in a section vertical to the surface, and with the margin of the shell lying in the direction of the left side of the drawing. a, Conical termination of sense-organ; b, b', ends of nerve; c, nerve; ƒ, calcareous cornea; g, lens; h, iris; k, pigmented capsule of eye; m, body of sense-organ cut across; n, nerve of eye; P, nerve of sense-organ; r, rods of retina

99. Long section through the front (A) and hinder (B) dorsal eyes
of Epeira diadema. A, Anterior eye; B, posterior eye; Hp,
hypoderm; Ct, cuticle; ct, boundary membrane; M, muscular
fibres; M, M', cross sections of ditto; St, rods; Pg, P1, pig-
ment cells; L, lens; Gk1, vitreous body; K, nuclei of the cells
of the retina; Kt, crystalline cones; Rt, retina; Nop, optic nerve
100. Section through the eye of a cockchafer (Melolontha)..
101. Section throngh the eye of a fly. b.m, Basilar membrane; c,

cuticle; e.op, epioptic ganglion; n.c, nuclei; n.c.s., nerve-cell
sheath; N.f, decussating nerve-fibres; op, optic ganglion; pc,
pseudocone; pg, pigment cells; p.op, perioptic ganglion; r, re-
tinula; Rh, rhabdom; T, trachea; t.a, terminal anastomosis;
Tt, trachea; ti, tracheal vesicle

102. Two separate elements of the faceted eye of a bee. Lf, Cornea; n, nucleus of Semper; Kk, crystalline cone; Pg, Pg', pigment cells; R, retinula; Rm, rhabdom

103. Eyelet of cockroach. If, Cornea; kk, crystalline cone; pg', pig-
ment cell; rl, retinula; rm, rhabdom
104. Eyelet of cockchafer. If, Cornea; kk, crystalline cone; pg, pg',
pigment cells; rl, retinula; rm, rhabdom

105. Leptodora hyalina

PAGE

143

145

147

148

149

150

152

152

106. Eye of Mysis. n, Nuclei; Lf, facets; Kk, crystalline cones;
n', cells of the retinula; R, retinula; Rm, rhabdom; Cp,
blood-vessels; N, fibres of the optic nerve; N11, N111, N1111,
decussations of the fibres of the optic nerve; G, G1, ganglia;
M, muscles for the movement of the eye-stalk; Km, nuclei

107. Corycæus. a, b, The eye
108. Eyes of Calanella Mediterranea.

Pg, pigment cells; N.fr,

frontal nerves; N.op, nervus opticus. The numbers show

157

158

the numbers of the cells

159

FIGURE

LIST OF ILLUSTRATIONS.

109. Diagram of a vertical section through a portion of the lateral eye of Limulus polyphemus, showing some of the conical lenses, and corresponding retinulæ. a, Cuticle; bb, cuticular lens; cc, hypoderm; Rn, retinula; n, nerves

xix

PAGE

160

161

162

110. Euphausia pellucida. l.o, Luminous organ
111. Luminous organ of Euphausia. f, Fibres; e, lens
112. Eye-stalk of Euphausia. lo, Luminous organ; a, lower eye
113. One of the elements of the eye of a fly. kk, Crystalline cone;
x, position of the image; s, rod; sc, sheath; scm, outer
sheath; r, retina; y, seat of vision

116. Edge of a portion of the mantle of Aglaura hemistoma, with a pair of sense-organs. v, Velum; k, sense-organ; ro, layer of nettle cells; t, tentacle

162

166

185

186

188

117. Sense-organ of leech. 1, Epithelium; 2, pigment; 3, cells; 4, nerve..

189

118. Daphnia pulex. a, Antennæ; b, brain; e, eye; h, heart; m, muscle of eye; n, nerve of eye; o, ovary; ol, olfactory organ; s, stomach; y, three eggs deposited in the space between the back and the shell

211

LIST OF THE PRINCIPAL

MEMOIRS, ETC.,

REFERRED TO IN THE PRESENT WORK.

Ahlborn, Zur Anat. und d. Ent. der Epi. b. Amphibien und Reptilien, Zool. Anz., 1886.

Allman, Mon. of the Hydroids, Ray Society, 1871.

Becher, Zur Kenntniss der Mundtheile der Dipteren, Denkschr. der Acad. d. Wiss. Wien., 1882.

Béla Haller, Untersuchungen über marine Rhipidoglossen, Morphol. Jahrb., 1884.

Beraneck, Ueber d. Parietal Auge der Reptilien, Jenaische Zeitschrift, 1887.

Berger, E., Unt. ü. d. Bau d. Gehirns u. d. Retina d. Arthropoden, Zool. Inst. Wien., 1878.

Bernstein, The Five Senses of Man.

Bevan, On the Honey Bee.

Blainville, De, Principes d'anatomie comparée.

Blix, Exper. Beit. z. Lösung d. Frage ü. d. Specif. Energie d. Hautnerven, Zeit. für Biologie, 1884.

Exper. Beit. z. Lösung d. Frage ü. d. Specif. Energie d. Hautnerven, Zeit. für Biologie, 1885.

Boll, F., Beiträge z. Phys. Optik, Arch. für Anat. Phys. u. Wiss. Medicin,

1871.

Bonnsdorf, Fabrica, usus, et differentiæ palparum in insectis.

Aboae, 1792.

Dissertatio.

Bourne, G. C., On the Anatomy of Sphærotherium. Linnean Journal,

1885.

Boyes, Capt., The Economy of the Paussidæ, Ann. and Magazine of Natural History, vol. xviii.

Brady, On the Copepoda of the Challenger Expedition, vol. viii.

xxii

MEMOIRS, ETC., REFERRED TO.

Breitenbach, Beit. z. Kennt. d. Baues d. Schmetterling-Rüssels, Jenaische Zeit., bd. xv.

Briant, T. T., On the Anatomy and Functions of the Tongue of the Bee, Journal of the Linnean Society, 1864.

Buchner, L., Mind in Animals.

Burmeister, Handbuch der Entomologie. 1885.

Carrière, J., Die Sehorgane der Thiere. 1885.

Claparède, E., Morphologie des zusammengesetzten Auges bei den Arthropoden. Zeit. für Wiss. Zool., 1860.

Anat. and Ent. d. Retina, Müller's Archiv, 1857.

Sur les pretendus organes auditifs des Antennes chez les Coléoptères, Ann. Sci. Nat., 1858.

Claus, Ueber den Acoust. App. im Gehörorgane der Heteropoden, Arch. für Mic. Anat., 1878.

Ueber einige Schizopoden und niedere Malacostraceen, Zeit. für Wiss. Zool., 1863.

Comparetti, Dinamica animale degli insetti. Padoue: 1800.

De aure interna comparata-Patavii. 1789.

Cornalia, Monografia del Bombice del Gelso, Mem. d. R. istit. Lombardo di science. Milano: 1856.

Dahl, Das Gehör-und Geruchsorgan der Spinnen, Arch. für Mik. Anat., 1885.

Earthworms.

Origin of Species.

Desvoidy, Robineau, Recherches sur l'organisation vertébrale des crustacés et des insectes.

Dönhof, Bienenzeitung, 1851 and 1854.

Dor, De la Vision chez les Arthropodes, Arch. d. Sci. Phys. et Nat. Genève : 1861.

Duméril, Considérations générales sur les insectes.

Du siège de la gustation chez les coléoptères, Comptes rendus de l'Acad. d. Sciences, 1886.

Eimer, Dr. Th., Ueber Tast-apparate bei Eucharis multicornis, Arch. für Mic. Anat., 1880.

Erichson, De fabrica et usu antennarum in insectis. Berlin: 1847. Exner, S., Ueber das Sehen von Bewegungen und die Theorie des zusammengesetzten Auges. Sitzungsber, Wien. Akad., 1875.

Die Frage der Functionsweise der Facettenaugen, Biol. Centralblatt, 1881, 1882.