LIST OF ILLUSTRATIONS. XIII 



Page. 



Cymothoa <> strum, a, young of the second stage, b, young of the first stage. 



c, lateral view of thorax of adult female, d, adult male, e, adult female. 



/', adult female 85 



Erixestus winnemana, adult female 



Erixestw winnemana, antenna of female 88 



Psylledontus insidiosus, adult female 89 



Psylledontus insidiosus, antenna of female 89 



Plagiomerus diaspidis, antenna of female 90 



Leptocerdale longipinnis 142 



Head of Leptocerdale longipinn is 143 



View of the Rio Pampas looking downstream 17S 



Bulimulus i Lissoacme) binghami 180 



Bulimulus {Lissoacme) ptyalum 181 



< llausilia I Nen in l pampasensis L82 



Fragment of a twig of Nagcioj>osis zamioides showing indications of decurrenl 



leaves and a spiral phyllotaxy : 1ST 



Twig of Nageioposis zamioides showing variation in form and size of leaves 192 



Pleuronichthys nephelus 283 



Pleuroit ichthys ocellatus 285 



Eucrangonyxserratus. 1, antenna. 2, antenna. 3, gnathopod. 4, gnathopod. 300 



E. serratus. Perseopod 5. 6, uropod. 7, telson 301 



E. serrat us (young) antenna, 8. 9, antenna. 10, gnathopod. 11, gnathopod. 



12, uropod 303 



E. gracilis (young). 13, gnathopod. 14, gnathopod. 15, uropod. Hi. E. 



serratus (young) telson. 17, E. gracilis (young > telson :'>D 1 



< 'ompsemys parva. Restoration of plastron 309 



Compsemys vafer. 2, first, second, and third neurals; 3, first and third right 



peripherals, with restoration of the second; 4, section of front end of eighth 

 peripheral; 5, section across tenth peripheral 311 



Basilemys prxclara. 6, lower surface of front end of plastron; ent, entoplastron; 

 epi, epiplastorn; gul, gular scute; intg, intergular scute; 7, section across 

 front end of plastron a little in front of entoplastron 314 



Basilemys prxclara. 8, median section of front of plastron; ent, entoplastron; 

 epi, epiplastron; 9, section of free border of xiphiplastron 40 mm. behind 

 hypoplastron 315 



Basilemys prxclara. 10, upper surface of front of nuchal; 11, section across 



nuchal near union with first peripheral 315 



Basilemys nobilis. 12, section across free border of xiphiplastron 40 nun. behind 

 hypoplastron; on the left the section enters depression for pubis; 13, section 

 across free border of xiphiplastron 1 L5 mm. behind hypoplastron 316 



Adociis vigoratus. 14, first neural; 15, first left peripheral; Hi, section across 

 firal left peripheral, the upper surface toward right; 17, left seventh periph- 

 eral; IS, section across free border of base of hinder lobe :>17 



Alamosemys annexa. Lower surface of the plastron 319 



Hoploch lys bicarinata. 20, front end of fourth peripheral — u, groove for process 

 of hypoplastron; b, lateral carina with groove above it; 21, hinder end of 

 fourth peripheral; 22, front, end of eighth peripheral — a, pit for process of 

 hypoplastron; 23, eighth, ninth, tenth , and eleventh peripherals 322 



Cypris {Cypris) globulus, a, right shell from within, X70; 6, dorsal view, X70; 

 c, furca, X210; d, second fool, X210 ■"<> 



Cypris {Cyprinotus) dentata. a, left shell of female, X<>0; b, left shell of male. 



X 60; c, right shell of male. <60; </. dorsal view of male, X<i<) : < : > : 



Cypris {Cyprinotus) dentata. ".furca. X105; 6, second leg, X250; c, maxillary 

 palp of male, X130; d, maxillary palp of male, X 130; e, penis 337 



