iLeuck- krt s Classifi cation. ZOOLOGY 809 Vlilne- iJdward: lassifi- ation. R. Leuckart s l classification is as follows : Type 1. Ccelenterata. Class I. POLYPI. Orders : Anthozoa and Cylicozoa. ,, II. ACALEPHJE. Orders : Discophorae and Ctcnopliorae. Type 2. Echinodermata. Class I. PKLMATOZOA. Orders : Cystidcci and Grinoidca. ,, II. ACTINOZOA. Orders : Echinida and Astcrida. ,, III. SCYTODEKMATA. Orders : Holothuriss and Sipunculida. Type 3. Vermes. Class I. ANEXTER.ETI. Orders : Ccstodcs and Acanthoccphali. ,, II. APODES. Orders : Nemertini, TurbcUarii, Trcmatodes, and Hirudinci. III. ClLIATI. Orders : Bryozoa and Rotifera. ,, IV. ANNELIDES. Orders : Ncmatodcs, Lumbricini, and Branchiati. Type 4. Arthropoda. Class I. CRUSTACEA. Orders : Entomostraca and Malacostraca. ,, II. INSECTA. Orders : Myriapoda, Araclmida (Accra, Latr. ), and Hcxapoda, Type 5. Mollusca. Class I. Tuxic ATA. Orders : Ascidiee and Salpee. ., II. ACEPHALA. Orders : Lamell ibranchiata and Brachiopoda. ,, III. GASTEROPODA. Orders : Hctcrobranchia, Dcrmatobranchia, Hctcro- poda,Ctenobranchia,Pulmonata,&i<.Cydobranchia. ,, IV. CEPHALOPODA. Type 6. Vertebrata. (Not specially dealt with.) The classification given Toy Henri Milne-Edwards 2 is as >s follows : Branch I. Osteozoaria or Vertebrata. Sub-Branch 1. Allantoidians. Class I. MAMMALIA. Orders : (a) Monodelphia : JBimana, Quadru- incma, Cheiroptera, Insectivora, Rodcntia, Edentata, Carnivora, Amphibia, Pachyder- inata, Ruminantia, Cetacca ; (b) Didelphia : Marsupialia, Monotremata. ,, II. BIRDS. Orders : Rapaces, Passcres, Scansorcs, Gallinse, Grallfe, Palmipedes. ,, III. REPTILES. Orders : Chdonia, Sauria, Ophidia. Sub-Branch 2. Anallantoidians. Class I. BATRACHIANS. Orders : Anura, Urodcla, Pcrcnnibranchia, Cojcilise. II. FISHES. Section 1. Ossei. Orders : Acanthopterygii, Abdominals, Sub- brachii, Apodcs, Loj)hobranchii,Plcetognathi. Section 2. Clwndroptcrygii. Orders : Sturiones, Sclachii, Cydostomi. Branch II. Entomozoa or Annelata. Sub- Branch 1. Arthropoda. Class I. INSECTA. Orders : Coleoptcra, Orthoptcra, Ncuroptcra, Hymenoptcra, Lcpidoptcra, Hemiptcra, Di- ptcra, Khipiptera, Anopleura, Thysanura. ,, II. MYRIAPODA. Orders: Chilognatha and Chilopoda. ,, III. ARACHNIDS. Orders : Pulmonaria and Trachcaria. 1 Die Morphologic und die Verwandtschaftsverhaltnisse der wirbd- losen Thiere, Brunswick, 1848. The Protozoa, recognized as a primary group by Siebold and Stannius (Lehrbuch d. veryleich. Anatomic, J5urlin, 1845), are not included at all by Leuckart in his scheme. The name Protozoa was first used by Goldfuss (1809) to include micro scopic animals and also the Polyps and Medusas, and Siebold and Stan nius first used it in its modern signification as comprising and limited to the Infusoria and Rhizopoda. C ours Elcmentaire d Histoire Natv.relle, Paris, 1855. Class IV. CRUSTACEA. Section 1. Podophthalmia. Orders : Dccapoda and Stomopoda. Section 2. Edriophthalmi. Orders: Amphipoda, Loemodipoda, and Isopoda. Section 3. Branchiopoda. Orders : Ostracoda, Phyllojmda, and Trilo- bitse. Section 4. Entomostraca. Orders : Copcpoda, Cladoccra, Siphono- stoma, Lcrn&ida, Cirriped.ia. Section 5. Xiphosura. (The orders of the classes which follow are not given in the work quoted. ) Sub-Branch 2. Vermes. Class I. ANNELIDS. Class IV. CESTOIDEA. ,, II. HELMINTHS. ,, V. ROTATORIA. ,, III. TUILBELLARIA. Branch III. Malacozoaria or Mollusca. Sub-Branch 1. Mollusca proper. Class I. CEPHALOPODA. ,, II. PTEROPODA. Sub-Branch 2. Molluscoidea. Class I. TUNICATA. Branch IV. Zoophytes. Sub-Branch 1. Radiaria. Class I. ECHINODERMS. ,, II. ACALEPHS. Sub- Branch 2. Sarcodaria. Class I. INFUSORIA. Class III. GASTEROPODA. ,, IV. ACEPHALA. Class II. BRYOZOA. Class III. CORALLARIA POLYPI. Class II. SPONGIARIA. In England T. H. Huxley adopted in his lectures (1869) Huxley s a classification which was in many respects similar to both classifi- of the foregoing, but embodied improvements of his own. ca It is as follows : Sub-Kingdom I. Protozoa. Classes : RHIZOPODA, GREGARINIDA, RADIOLARIA, SPONGIDA. Sub- Kingdom II. Infusoria. Sub-Kingdom III. Coelenterata. Classes : HYDROZOA, ACTINOZOA. Sub-Kingdom IV. Annuloida. Classes : SCOLECIDA, ECHINODERMATA. Sub-Kingdom V. Annulosa. Classes : CRUSTACEA, ARACHNIDA, MYRIAPODA, INSECTA, CH.E- TOGNATHA, ANNELIDA. Sub-Kingdom VI. Molluscoida. Classes : POLYZOA, BRACHIOPODA, TUNICATA. Sub-Kingdom VII. Mollusca. Classes : LAMELLIBRANCHIATA, BRANCHIOGASTROPODA, PULMO- GASTROPODA, PTEROPODA, CEPHALOPODA. Sub-Kingdom VIII. Vertebrata. Classes : PISCES, AMPHIBIA, REPTILIA, AVES, MAMMALIA. We now arrive at the period when the doctrine of organic evolution was established by Darwin, and when naturalists, being convinced by him as they had not been by the transmutationists of fifty years earlier date, were com pelled to take an entirely new view of the significance of all attempts at framing a " natural " classification. Many zoologists prominent among them in Great Classifi- Britain being Huxley had been repelled by the airy fancies cations and assumptions of the " philosophical " morphologists. ; a se The efforts of the best minds in zoology had been directed ture for thirty years or more to ascertaining with increased accuracy and minuteness the structure, microscopic and gross, of all possible forms of animals, and not only of the adult structure but of the steps of development of that structure in the growth of each kind of organism from the egg to maturity. Putting aside fantastic theories, these observers endeavoured to give in their classifications a strictly objective representation of the facts of animal structure and of the structural relationships of animals to one another capable of demonstration. The groups within groups adopted for this purpose were necessarily wanting in symmetry : the whole system presented a strangely irregular character. From time to time efforts were made by those who believed that the Creator must have followed a symmetrical system in his production of animals to force one or other artificial, neatly balanced
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