Annelids

Oviparous animals with an elongated body, which is soft and ringed laterally, rarely having eyes and a distinct head, and lacking articulated limbs. Arteries and veins for circulation; respiration by gills; a longitudinal ganglionic chord.

In the annelids, nature is forced to abandon the method of articulation which she has constantly used with the insects, arachnids, and crustaceans.

Their bodies are elongated, soft, and mostly composed of simple rings.

This gives these animals the appearance of being just as imperfect as the worms, with whom people have confused them.

But since they have arteries and veins and breathe by gills, these animals, very distinct from the worms, must, along with the cirripeds, make the transition from the crustaceans to the mollusks.

They lack articulated limbs (2), and most of them have, on the side, bristles or bundles which take the place of limbs. Almost all of them are suckers and feed themselves only on fluid material.

Table of Annelids

First Order: Cryptobranch Annelids

Planaria Leech Lernia Clevella

Furia (?) Nais Lumbricus Thalassema

Second Order: Gymnobranch Annelids

Arenicola Amphinoma Aphrodite Nereis

Terebella Amphitrite

Sabellaria

Serpula Spirorbis Siliquaria Dentaliium

Cirripeds

(Ninth Class of the Animal Kingdom)

Oviparous and testaceous animals without a head and eyes, having a mantle which covers the inside of the shell, articulated arms with a horny skin, and two pairs of jaws in the mouth; respiration by gills; a longitudinal ganglionic chord; vessels for circulation.

Observations

Although we know only a small numbers of general which are linked to this class, the characteristics of the animals which make up these genera are so remarkable that it is necessary that we distinguish them as making up a specific class.

The cirripeds have a shell, a mantle, and have no head or eyes. Thus they cannot be crustaceans. Their articulated arms mean that we cannot place them among the annelids. And their longitudinal ganglionic chord prevents us from combining them with the mollusks.

Table of Cirripieds

Tubicinella Coronula

Balanus Anatifa

Remarks: We see that the cirripeds still incline towards the annelids by their longitudinal ganglionic chord. But in these animals, nature is preparing itself to create the mollusks, because they already have, as do the latter, a mantle which covers the interior of their shell.

Mollusks

(Class Ten of the Animal Kingdom)

Oviparous animals, with a soft body (not articulated in its parts) and a variable mantle; respiration by very diversified gills; no spinal chord, no longitudinal ganglionic chord; nerves ending at an imperfect brain.

Most of them are enveloped in a shell; others have a shell more or less entirely enclosed in their interior; and still others have no shell at all.

Observations

The mollusks are the best organized of the animals without vertebrae, that is to say, those whose organic structure is is the most complex and which come closest to that of fish.

They make up a numerous class which ends the invertebrates and which is really distinguished from the other classes, since the animals which make it up have a nervous system, like many others, but are the only ones which have neither a longitudinal ganglionic chord nor a spinal chord.

Nature, at the point of starting to form the system of organic structure of the vertebrate animals, appears here to be preparing herself for this change. Thus the mollusks, which have no link any more to the style of articulation and of the attachment which a horny skin gives for the muscles of animals who have this feature, are very slow in the movements and appear, in this respect, more imperfectly structured than even the insects.

Finally, since the mollusks make the transition from invertebrates to vertebrate animals, their nervous system is intermediate, and displays neither the longitudinal ganglionic chord of the invertebrate animals with nerves nor the spinal chord of the vertebrate animals. This is eminently characteristic of them and clearly distinguishes them from the other invertebrates.

Table of Mollusks

Order One: Acephalic Mollusks

No head, no eyes, no organs for chewing; they reproduce without copulation; most of them have a shell with two valves which articulate with a hinge.

Brachiopods

Lingula Terebratules Orbicules

Ostracians

Radiolites Calceola Crania Anomia Placuna Vulsella

Oyster Gryphaea Plicatula Spondylus Pecten

Byssifera

Houlette Lima Pinna Perna Malleus

Mytilus Modiola (?) Crenatula Avicula

Chamaceans

Etheria Chama Diceras

Corbula Pandora

Naiads

Mulette Anodonta

Arcaceans

Nucula Petunculus Arca

Cucullaea Trigonia

Cardiads

Tridaena Hippopus Cardita

Isocardia Cardium

Conchs

Venericardia Venus Cytherea Donax Tellina

Lucina Cyclas Galathea Capsa

Mactraceans

Erycina Ungulina Crassatella

Lutraria Mactra

Myarians

Mya Panorps Anatina

Solenaceans

Glycimeria Solen Sanguinolaria

Petricola Rupellaria Saxicava

Pholadarians

Pholas Teredo Fistulana

Aspergillum

Ascidians

Ascidia Salpa Mammaria

Order Two: Cephalic Mollusks

A distinct head, eyes and two or four tentacles in most, jaws or a proboscis by the mouth; reproduction by coupling; the shell in those which have one never consists of two articulated valves with a hinge.

(1) Pteropods

Two opposed fins for swimming

Hylaea Clio Pneumoderma

(2) Gasteropods

(A) straight body, unified to the foot in all or almost all its length.

Tritonians

Glaucus Aeolis Scyllaea

Tritonia Tethys Doris

Phyllidians

Pleurobranchus Phyllidia Chiton

Patella Fissurella Emarginula

Laplysians

Laplysia Dolabella

Bullaea Sigaretus

Limacians

Onchidium Limax Parmacella

Vitrina Testacella

(B) Spiral body; no siphon

Colymaceans

Helix (snail) Helicina Bulimus

Amphibulimus Agathina Pupa

Orbaceans

Cyclostoma Vivipara

Planorbis Ampullaria

Auriculaceans

Auricula Melanopsis

Melania Limnaea

Neritaceans

Neritina Navicella

Nerita Natica

Stomataceans

Haliotis Stomatia Stomatella

Turbinaceans

Phasianella Turbo Monodonta Dauphinula

Scalaria turritella Vermicularia(?)

Heteroclites

Volvaria Bulla Janthina

Calyptraceans

Crepidula Calyptraea

Solarium Trochus

Canalifera

Cerithiium Pleurotoma Turbinella Fasciolaria

Pyrula Fusus Murex

Wing Shells

Rostellaria Peteroceras Strombus

Purpuraceans

Cassis Harpa Dolium Terebra Eburna

Buccinum Concholepas Monoceros Purpura Nassa

Columellarians

Cancellaria Marginella Colombella

Mitra Voluta

Convolutes

Ancilla Oliva Terebellum

Ovula Cypraea Conus

(3) Cephalopods

(A) with multilocular test

Lenticulaceans

Miliola Gyrongonita Rotalia Renulites

Discorbina Lenticulina Nummulites

Lituolaceans

Lituolites Spirolinites Spirula

Orthocerae Hippurites Belemnites

Nautilaceans

Baculites Terrilites Ammonoceras

Ammonites Orbulites Nautilus

(B) With unilocar test

Argonautaceans

Argonauta Carinaria

Sepialeans

Octopus Calamary Cuttle-fish