Structure of shell 34 " of the individual compartments 43 " of the radii 45 " of the alæ 47 " of the sheath 48 " of the basis 49 " of the opercular valves (scuta and terga) 51 Growth of whole shell and 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, last or pupal stage 110 Act of metamorphosis 126 On the homologies of the carapace 131 Cementing apparatus 133 Affinities, classification, variation 152 Rate of growth, exuviation, &c. 156 Geographical range and habitats 159 Geological history 172