540 THE ANIMAL KINGDOM. 



1. Leptostraca (= Nebalia) \ 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. 



(/3) 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 (Mysis, &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. 



() 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, and except Cirripedia, Baird, British Entomostraca, Ray Soc. 1850. 



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

 Geol. Survey, xii. 1883. Branchipus and Artemia, Claus, 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, Claus, 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, Claus, Schriften Zool. Inhalts. Wien, 1874. Cypridinae, Id. Z. W. Z. xxiii. 

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

 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, Me"m. Inst. Genev. xiii. 1877 ; Lernaeidae, Claus, Marburg 



