520 RICHARD SWANN LULL ON 



This genus as at present restricted coiitiiiiis hut two species, T. (iiKjufttus (E. Hitch- 

 cock) and 1\ eh(j(ins (C.H.Hitchcock). The uame Plectropterna unfortunately cannot 

 be retained, as the type species, P. minitans, pro\es to he synonymous with Anonibejms 

 intennediuH, the oUI generic name becoming thus a synonym for Anonioepus. 



The type species is Tdrsoiih'cfnix aur/iisfus. 



Tarsoplectrus angustus (K. Ilitcluock). 

 Plectroptenia (i/Kjusfa E. Hitchcock, '58. p. 11", pi- 1«S, hg. 4 ; pi. 30, tig. 3. 



Specific characters. Pes: divarication of digits 1 and 11, !)5° ; of H and 111, 22°; 

 of HI and IV, 25°; of 11 and IV, 47°. Length of digit 1, .018 m.; of II, .051 m.; of 111, 

 .071 m.; of IV, .046 m. Distance hetween lateral tips, .04(1 m. Length of foot, .110 m. 

 Length of step, .305 m. Widtli of trackway, .068 m. Toes slightly curved. Hallux 

 strongly recurved arising about the middle of the length of the heel. 



Type specimen, no. ||, of the Hitchcock caljinet, from Turner's Falls, Massachusetts. 



Tarsoplectrus elegans (C. H. Hitchcock). 

 Plectropterna elegans C. H. Hitchcock, '89b, pp. 122, 125. 



Specific characters. Pes : divarication of digits II and 111, 30° ; of III and IV, 40° ; 

 of II and IV, 70°. Length of digit I, .023 m.; of II, .026 to .045 m.; of HI, .051 to .076 

 in.; of IV, .038 to .045 ui. Length of foot, .127 to .132 m. Distance between lateral 

 tips, .050 to .000 ni. Length of step, .457 to .533 m. Width of trackway, .077 m. 



Type specimens, nos. 53, Ul, and 242, in the Mt. Holyoke cabinet, from Weathers- 

 field, Connecticut. 



Genus Polemarchus E. Hitchcock. (A leader in war.) 

 Polemarchtis E. Hitchcock, '45b, p. 24 ; '58, p. 107, pi. 18, fig. 1; pi. 5'.', fig. 3. 



freneric characters. Bipedal, tetradactyl, plantigrade, with broad heel and with a 

 large, half rotated hallux. Toes slender in the track, but the latter, which is of shale, 

 has doubtless caved in to some extent. No pads nor claws in evidence. 



Except for the presence of the hallux this form most nearly approximates Platyp- 

 terua. There is hut one extremely rare species: Polemarrhns giyas. 



Polemarchus gigas E. Hitchcock. 



Polemarclms gigas E. Hitchcock, '45b, p. 24; '58. p. 107. ])1. IS, fig. 1 ; pi. 59, fig. 3. 

 Specific characters. Pes: divarication of digits 1 and 11, 61"; of 11 and HI. 20°; of 



