540 THE ANIMAL KINGDOM. 



1. Leptostraca (= Nelalia) \ bivalve shell; eight thoracic somites free; abdo- 

 men of eight somites -, with furcae anales ; thoracic limbs Phyllopod-like. Nebalia. 



2. Arthrostraca : seven, rarely six free thoracic somites ; eyes sessile ; no 

 cephalothoracic shield. 



(a) Amphipoda : body laterally compressed ; branchiae on thoracic limbs ; 

 first three pairs of abdominal feet natatory : e. g. Caprella, Cyamus, Talitrus, Or- 

 chestia, Gammarus, Hyperia, Phronima. 



(j3) Isopoda: body more or less compressed dorso-ventrally ; first pair of 

 abdominal feet form an operculum, covering the other pairs which are branchiate : 

 e. g. Tanais, Anceus, Cymothoe, Anilocra, Serolis, Idotea, Asellus, Bopyrus, Entoniscus, 

 Ligia, Oniscus, Armadillo. 



3. Thoracostraca : all or some thoracic somites fused to head ; a cephalo- 

 thoracic shield ; eyes mostly stalked. 



(a) Cumacea : 4-5 free thoracic somites ; two pairs of maxillipeds ; abdomen 

 in c? carrying two, three, five pairs of natatory feet ; eyes sessile : e. g. Cuma 

 (=Diastylis\ &c. 



() Stomatopoda : short cephalothoracic shield ; five pairs of maxillipeds ; 

 branchiae on abdominal feet; abdomen large; e.g. Squilla. 



(y) Podophthalmata : large cephalothoracic shield ; two to three pairs of 

 maxillipeds. (i) Schizopoda : thoracic feet (eight pairs) biramose (My sis, &c.). 



(ii) Decapoda : thoracic somites fused to head ; five last pairs of 

 thoracic feet uniramose and seven-jointed. 



(a) Abdomen long, Macrura ; e. g. Lucifer, Sergestes, Penaeus, Palaemon, 

 Craugon, Astacus, Nephrops, Scyllarus, Palinurus, Pagurus, Birgus. 



(b) Abdomen short, Brachyura-, e.g. Dromia, Maja, Cancer. 



See lit. pp. 176-7, 181, 186, 189. 



A. Entomostraca, Gerstaecker, Bronn's Class, und Ordn. des Thierreichs,v. Abth. 

 i. 1866-79, an d except Cirripedia, Baird, British Entomostraca, Ray Soc. 1850. 



Phyllopoda : Branchiopoda, Packard, ' North American PhyllopodaJ Rep. U. S. 

 Geol. Survey, xii. 1883. Branchipus and Artemia, Glaus, Arb. Zool. Inst. Wien, vi. 

 1886. Limbs of Apus, Ray Lankester, Q. J. M. xxii. 1882 ; Packard, ' Homologies,' 

 &c. American Naturalist, xvi. 1882. Estheria and Limnadia, Gruber, A. N. 31 (i), 

 1865. Limnadidae, Klunzinger, Z. W. Z. xiv. 1864. 



Cladocera-. Polyphemidae, Glaus, Dk. Akad. Wien, xxxvii. 1877. Daphnidae, Id. 

 Z. W. Z. xxvii. 1876. New British sp., Ray Lankester, A. N. H. (5), ix. 1882. Lep- 

 todora, Forrest, Journal Roy. Micr. Soc. ii. 1879 ; Weismann, Z. W. Z. xxiv. 1874. 



Ostracoda-. Cytheridae, Kaufmann, Recueil Zool. Suisse, iii. (2), 1886. Halocy- 

 pridae, Glaus, Schriften Zool. Inhalts. Wien, 1874. Cypridinae, Id. Z. W. Z. xxiii. 

 1873; Zenker, Monograph, A. N. xx. (i) 1854. Brady, 'Recent British Ostracodaj 

 Tr. L. Soc. xxvi. 1870; Id. Ostracoda, Challenger Reports, i. 1880. 



Copepoda: Brady, 'Free and semi-parasitic Copepoda] 3 vols. Ray Soc. 1878- 

 1880 ; Id. Copepoda, Challenger Reports, viii. 1883 ; cf. Baird's British Entomostraca, 

 Ray Soc. 1850. Cyclops, Hartog, J. L. S. xviii. 1885. Development, Urbanovics, 

 Z. A. vii. 1884; and of Cetochilus, Grobben, Arb. Zool. Inst. Wien, iii. 1881. 

 Generative organs of free Copepoda, Gruber, Z. W. Z. xxxii. 1879. Parasitic forms : 

 Chondracanthidae, Vogt, Mdm. Inst. Genev. xiii. 1877 ; Lernaeidae, Clous, Marburg 



