LIST OF ILLUSTRATIONS. XI 



Page 



A. assimilis, anterior end, dorsal aspect, of specimen from Uschuaia. The 

 prostomium is in a state of normal extension 18 



A. assimilis, var. affinis, anterior end, dorsal aspect of specimen from the Falk- 

 land Islands. The prostomium is protruded to its fullest extent. X6. L, 

 lateral lobe of prostomium; if, median lobe; iV^, first notopodium ; P, median 

 posterior portion of prostomium ; Ph, pharynx 18 



A. cristata, anterior end, dorsal aspect of a specimen from Florida. X4. L, 

 lateral lobe of prostomium; L, N, lip of nuchal organ; M, median lobe of 

 prostomium; N^, first notopodium; Ph, pharynx 21 



A. glacialis, ninth gill of No. 8. Three of the axes are cut off. X 15 26 



A. glacialis, third gill of No. 6. Thi-ee of the axes are cut off. X 35 26 



A. glacialis, anterior end, dorsal aspect. X 6. L, lateral lobe of prostomium; 

 LN, lip of nuchal organ slightly everted; M, median lobe of prostomium; 

 N'', first notopodium (the notopodium is retracted, leaving a slit on the sur- 

 face) ; N. Gr, nuchal groove 27 



A. glacialis, diagram representing the annulation of the anterior end. X4. 

 N^, first notopodium 27 



A. glacialis, neuropodial crotchets. A and B were found together, the crotchet 

 B was in use, A is one of the two small crotchets found in this neuropodium. . 29 



Neoseps reynoldsi 34 



Neoseps reynoldsi. 2, top of head; 3, side of head; 4, imderside of head; 5, fore 

 leg; 6, hind leg 35 



Mesotergum and base of right wing of Txniopteryx frigida (stonefly), showing the 

 wing-bearing notum (iV) and the postnotum (PN): A, anal vein; ANP, ante- 

 rior notal wing process; lAx, first axillary; ^Ax, second axillary; 3Ax, third 

 axillary; AxC, axillary cord; C, costa; Cu cubitus; M, media; m, median plate 

 of wing base; iV, notum; PN, postnotum; PNP, posterior notal wing process; 

 Pph, postplu-agma; Psc, precutal differentiation of notum; R, radius; Rd, 

 posterior marginal reduplication of notum; Sc, subcosta; Tg, tegula 43 



Mesotergum of Blatella germanica (cockroach), dorsal view, illustrating a tergum 

 consisting of a notal plate alone; a, chitinous fold reflected upon posterior 

 edge of protergum; ANP, anterior notal wing process; anr, line formed by 

 anterior ventral notal ridge; AxC, axillary cord; PNP, posterior notal wing 

 process; pnr, line formed by posterior ventral notal ridge; Rd, posterior redu- 

 plication of the notum; vnr, line formed by median ventral V-shaped notal 

 ridge 44 



Ventral view of mesotergum of Blatella germanica: ANR, anterior notal ridge; 

 PNR, posterior notal ridge; VNR, median V-shaped notal ridge, the "ento- 

 dorsum" 44 



Mesotergum of Holorusia grandis (cranefly), showing division of notum into 

 three parts {Psc, Set, and Scl), back of which is postnotum (PN): AxC, axil- 

 lary cord; ANP, anterior notal wing process, PN, pn, postnotum; PNP, pos- 

 terior notal wing process; Pph, postphragma; Psc, prescutum; Rd, posterior 

 reduplication of notum; ^ScZ, scutellum; Set, scutum; u, lobe of prescutum 

 before base of wing 45 



Metathorax of Tseniopteryx frigida (stoneQy), left side, wings removed: Cx, coxa; 

 CxP, pleural coxal process; Epm, epimerum; Eps, episternum; F, base of 

 femur; N, notum; P, episternal parapterum; PN, postnotum; PS, pleural 

 suture; q, sternopleiu"al suture; S, sternum; Tn, trochantin; Tr, trochanter; 

 WP, pleural wing process ' 46 



Left metapleiu-um of Tseniopteryx frigida (stonefly) internal; c, sclerite connect- 

 ing parapterum (P) with head of costal vein of wing; Epm, epimerum; Eps, 

 episternum; P, episternal parapterum; PA, pleural arm; PN, lateral part of 

 postnotum, continuous with epimerum; PR, pleural ridge; S, sternum; Tn, 

 trochantin ; TFP, pleural wing process 46 



