ENTOMOSTRACA. 



[ 289 ] 



ENTOMOSTRACA. 



tenure two pairs, large ; eyes stalked 

 (n. 19. %. 26). 



Fani. 3. DiTmiirDA. Bivalve. 

 Lininadia, Estheria, Limnetis, 



Order 2. Cladocera. Legs four to six pairs, 

 cliietiy branchial ; eye single, and very 

 large ; antennte two pairs, inferior large, 

 branched and adapted for swimming. 



Fam. 1. Daphniad.e. Superior antennae 

 small ; inferior large, two-branched ; 

 legs live or six pairs, all enclosed within 

 the carapace; eye single, large. 



* (Daphnina.) Legs five pairs ; inferior 

 auteunaj two-branched, one branch f oui-, the 

 other three-jointed. 



Daphnia. Head produced below into 

 a beak ; superior autenuaj very small 

 (PI. 20. fig. 26). 



Moina. Head rounded and obtuse ; su- 

 perior antennae large (PI. 19. tig. 20). 



Macrothrix. Head beaked, beak di- 

 rected forwards ; superior antennae 

 one-jointed, hanging from the beak 

 (PI. 19. fig. 25). 



Bosmina. Head terminating in a sharp 

 dii'ect beak ; superior antennae long, 

 mauv-iointed, projecting from end of 

 beali (PI. 20. fig. 2). 



Drepmiothrix, Lathonura, Acantholehei'is, 

 Ilyocryptus. 



** (Sidina.) Legs six pairs ; inferior an- 

 tennae two-branched ; a row of spines arising 

 from the edge of larger branch ; superior 

 antennae of moderate size. 



Sida. One branch of inferior antennae 

 three-, the other two-iointed (PI. 19. 

 fig. 27). 



Daphnellu. Both branches two-iointed 

 (PI. 20. fig. 27). 



Fam. 2. Polypheshd^. Inferior antennae 

 two-branched, one branch four-, the 

 other three-jointed; lower part of shell 

 forming a large vacant space for con- 

 taining the ova and young ; eye very 

 large ; legs four paii's, not contained 

 within the shell. 



Polyphemus. Tail-like abdomen project- 

 ing outside the shell : freshwater (PI. 

 19.' fig. 29). 



Evadne. Abdomen scarcely projecting 

 from the shell ; marine (PI. 19. fig. 30). 



Fam. 3. LYNCEiD.ii;. Superior antennas 

 very short; inferior of moderate size, 

 branched, each branch three-jointed; 

 legs five pairs ; eye single, with a black 

 spot in front ; intestine convoluted, 

 having one complete turn and a half. 

 Eurycercits. Shell subquadrangular, ab- 

 domen forming a fiat, densely serrated 

 plate (PI. 20. fig. 39). 

 Chydorus. Nearly spherical ; beak very 

 long, sharp, and curved ; inferior an- 

 tennas very short (PI. 20. fig. 7). 

 Camptocercus. Ovoid ; abdomen long, 

 slender, and very flexible, serrated (PI, 

 20. tig. 4). 

 Acropenis. Somewhat harp-shaped, with 

 an anterior inferior obtuse angle ; infe- 

 rior antennae rather long (PI. 19. tigs. 

 1,2). 

 Alonn. Quadrangular, striated or grooved 

 longitudinally ; inferior antennae short 

 (PI. 19. tigs. 4, 5). 

 Plewoxas. Giblaous above and anterior- 

 ly ; obliquely truncate below ; first pair 

 of legs very large (PI. 19. fig. 32). 

 Peracantlm. Oval, lower end with a 

 curved posterior point, fringed infe- 

 riorly and antero-superiorly with strong 

 hooked spines (PI. 19. fig. 31). 

 Monospilus. 



See Crustacea and Siphonostoma. 

 BiBL. Baird, Br. Entom. ; M. -Edwards, 

 Cnistac. iii. ; Straus, Mem. Mits. 1819, v. 

 380, and 1821, vii. 33; Koch, Beutsclil. 

 Crustac. ; Desmarest, Crustac. ; Jones, En- 

 tom. Cretac. Form. {Palceont. Sac); Entom. 

 Tert., and Foss. Edherice ; Zencker, Miiller^s 

 Archiv, 1851 {Micr. Tr. i. 273) ; Morris, 

 Brit. Foss. 98 ; Lubbock, Linn. Tr. xxiii. 

 176, and xxiv. 197 ; Dana, Classif. Crust. 

 1853, Report on Crust. U. S. Exped. 1855 ; 

 Baird, A^in. N. Hist. 1862, ix. 132, and x. 1; 

 Grube, Esth. m. Limnad., Archiv Nat. xxxi. 

 1865 ; Plateau, Ann. iV. H. 1869, iii. 12 ; 

 Schcedler, Cladocera (3 pi.), 1863; Brady, 

 Ann. N. H. 1864, xiii. 59 {New Ostracoda) ; 

 1868, ii. (Ostr. from Scandinavian Seas, 

 Mauritius, c^'c); 1869, iii. 45; lA.. Linn. Tr. 

 1868, xxvi. 353 (Monoyr. Ostracoda) ; and 

 Copepoda {Ray Soc.) ; Norman and Brady, 

 Monogr. 1867; Sars, Orersiyt af Norges 

 Mar. Ostrac. 1865 ;^ Lilljeborg, De Crusta- 

 ceis, 1853; Zencker, Mull. Arch. 1850 {Cy- 

 pris) ; ibid. 1851 ; id. Arch. Naturg. 1854 ; 

 Hartog, J7i. Mic. S. 1880, 243 ; Brady and 

 Robertson, Ann. N. H. 1872, ix. 48 ; & Tr. 

 Palceontog. Soc. xxviii. ; Clans, Copepoda, 

 1881 ; and the BiBi.. of the genera. 



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