A MONOGRAPH ON THE SUB-CLASS CIRRIPEDIA (VOL. 2 OF 2) THE BALANIDÆ, (OR SESSILE CIRRIPEDES); THE VERRUCIDÆ, ETC., ETC. By Charles Darwin CONTENTS Page Dedication v Preface vii Monograph on the Cirripedia 1 Introduction 1 On the Names given to the different parts of Cirripedes 3 Class Crustacea, Sub-Class Cirripedia 9 On the Sexual Relation of Cirripedes 23 Order I.-Thoracica 30 Family Balanidæ 33 Table of Contents 33 Structure of Shell 34 Structure of the Individual Compartments 43 Structure of the Radii 45 Structure of the Alæ 47 Structure of the Sheath 48 Structure of the Basis 49 Structure of the Opercular Valves (Scuta and Terga) 51 Growth of the Whole Shell, and Its Microscopical Structure 54 Muscles of Sack 61 Branchiæ 63 Thorax and Body 65 Muscular System 68 Movements and Muscles of the Cirri 71 Mouth 74 Cirri 81 Caudal Appendages 85 Alimentary Canal 85 Circulatory System 87 Nervous System 88 Eyes and Vision 93 Acoustic Organs 95 Olfactory Sacks 97 Male Organs of Generation 97 Female Organs of Generation 100 Metamorphoses and Homologies 102 Larva, First Stage 103 Larva, Second Stage 109 Larva in the Last or Pupal Stage 110 Act of Metamorphosis 126 On the Homologies of the Carapace and Shelly Valves 131 Cementing Apparatus 133 Affinities, Classification, Variation 152 Rate of Growth, Exuviation, Powers of Repairing Injuries 156 Geographical Range and Habits 159 Geological History 172 Sub-Family Balaninæ 175 1. Genus Balanus 177 Sections of the Genus 193 Section A 194 1. Balanus tintinnabulum 194 Var. communis, vesiculosus, validus, zebra, crispatus, spinosus, coccopoma, concinnus, intermedius, occator, d'Orbignii Varieties 201 2. Balanus tulipiformis 204 3. Balanus psittacus 206 4. Balanus Capensis 209 5. Balanus Nigrescens 210 6. Balanus decorus 212 7. Balanus vinaceus 213 8. Balanus Ajax 214 Section B 216 9. Balanus stultus 216 10. Balanus calceolus 218 11. Balanus galeatus 220 12. Balanus cymbiformis 221 13. Balanus navicula 221 Section C 223 14. Balanus trigonus 223 15. Balanus spongicola 225 16. Balanus lævis 227 Var. nitidus, Coquimbensis 17. Balanus perforatus 231 Var. angustus, Cranchii, fistulosus, mirabilis 18. Balanus concavus 235 19. Balanus amphitrite 240 Var. communis, venustus, pallidus, niveus, modestus, Stutsburi, obscurus, variegatus, cirratus Varieties 245 20. Balanus pocilus 245 21. Balanus eburneus 248 22. Balanus improvisus 250 Var. assimilis 23. Balanus nubilus 253 24. Balanus corrugatus 254 Section D 256 25. Balanus porcatus 256 26. Balanus patellaris 259 27. Balanus crenatus 261 28. Balanus glandula 265 Section E 267 29. Balanus balanoides 267 Varieties 270 30. Balanus cariosus 273 31. Balanus declivis 275 Section F 277 32. Balanus Hameri 277 33. Balanus amaryllis 279 34. Balanus allium 281 35. Balanus cepa 283 36. Balanus quadrivittatus 284 37. Balanus terebratus 285 38. Balanus vestitus 286 39. Balanus Imperator 288