Rules for nomenclature. The rule of priority. Terminology and convenience. PART II. SYSTEMATIC. CHAPTER VII. =THALLOPHYTA.= Pp. 116–228. =PAGE= I. =PERIDINIALES= 117–118 II. =COCCOSPHERES AND RHABDOSPHERES= 118–121 III. =SCHIZOPHYTA= 121–138 A. SCHIZOPHYCEAE (CYANOPHYCEAE) 122–132 _Girvanella_ 124–126. Borings in shells 127–129. _Zonatrichites_ 129–130. B. SCHIZOMYCETES (BACTERIA) 132–138 _Bacillus Permicus_ 135–136. _B. Tieghemi_ and _Micrococcus Guignardi_ 136. Fossil Bacteria 137–138. IV. =ALGAE= 138–205 Scarcity of fossil algae. Fossils simulating Algae. Recognition of fossil algae. _Algites &c._ A. DIATOMACEAE 150–156 Recent Diatoms. Fossil Diatoms. _Bactryllium &c._ B. CHLOROPHYCEAE 156–178 _a._ SIPHONEAE 157–177 α. =Caulerpaceae= 157–159 β. =Codiaceae= 159–164 _Codium_ 159–160. _Sphaerocodium_ 160. _Penicillus_ 161. _Ovulites_ 161–164. _Halimeda_ 164. γ. =Dasycladaceae= 164–177 _Acetabularia_ 165–166. _Acicularia_ 166–169. _Cymopolia_ 169–171. _Vermiporella_ 172–173. _Sycidium_ 173. _Diplopora_ 174–175. _Gyroporella_ 175. _Dactylopora_, Palaeozoic and Mesozoic Siphoneae 175–177. _b._ CONFERVOIDEAE 177–178 C.INCERTAE SEDIS 178–183 Boghead ‘Coal.’ _Reinschia_ 180–181. _Pila_ 181–182. D. RHODOPHYCEAE 183–190 CORALLINACEAE 183–190 _Lithothamnion_ 185–189. _Solenopora_ 189–190. E. PHAEOPHYCEAE 191–202 _Nematophycus_ 192–202 _Pachytheca_ 202–204 _Algites_ 204–205 V. =MYXOMYCETES (MYCETOZOA)= 205–206 _Myxomycetes Mangini_ 206.