History of British animals - University of Guam Marine Laboratory

(224)INVERTEBRAL ANIMALS.[. GANGLIATA. — Brain surrounding the gullet, and5sending out nervous filaments, which in their course expand into ganglia.Class I. Mollusca.— Brain surrounding the gullet, and sendingout filaments, which separate irregularly.v Class. II. Annulosa.— Brain surrounding the gullet, and sendingout a knotted tilament to the posterior extremity ofthe body.II. RADIATA.— Nervous system obscure, disseminated,not appearingin the form of a collar round the gullet,nor of a longitudinalcord.Although the Radiata appear here as the last of the Invertebral Animals,it is my intention to proceed to the consideration of the species which belongto the division immediately after the enumeration of the Mollusca. Thiscourse I am induced to follow, because an intimate relationship appears tosubsist between certain groups of radiated and molluscous animals. Besides,by such an arrangement, the whole of the Annulose animals will remain connected,and occupy exclusively the second volume of this work.3