204 Zoologica: N. Y. Zoological Society [HI;? 



present; ninth small, ventrally reduced (9 Plate VII, figs. 1 and 

 2), witliout cerci; tenth {10 Plate VII, figs. 1 and 2) elongate 

 conical, developed as a locomotory organ with extrusible, mem- 

 branous anal lobes {I Plate VIII, fig. 2). 



Head exserted beyond, or slightly retracted into anterior 

 portion of prothorax ; type of head porrect with frons horizontal 

 and mouthparts stretched forward; form of head subtriangular 

 with posterior part broader. Occipital foramen posterior, annu- 

 lar, dorsally limited by hind margin of epicranium, ventrally 

 by hind margin of gular plate {gu Plate VII, fig. 7) . No collum. 

 Frons lyriform, one pair of oblong spots where frontal sutures 

 anteriorly begin to diverge (Plate VIII, fig. 9). Frons and 

 clypeus fused. Clypeus large, projecting to near tip of mandible, 

 trapezoidal with sides converging forward, chitinized. Labrum 

 short, soft and whitish, developed as a fleshy anterior margin of 

 clypeus (Plate VIII, fig. 9) . Epicranical halves dorsally entirely 

 separated by frons; no median, epicranical suture; hypostoma 

 (the epicranial margin between ventral articulation of mandible 

 and attachment of posterior tip of cardo) (hy Plate VII, fig. 7) 

 longitudinal with transverse curvation below cardo ; epicranial 

 margin longitudinally continued from tip of cardo to foramen 

 occipitale. Gula median, unpaired, hexagonal, without paragular 

 regions, chitinous, forming the ventral base of cranium between 

 mentum (or probably fusion of mentum and submentum), the 

 maxillary articulating area (r Plate VII, fig. 7), the epicranium 

 and the presternal region of prothorax. Hypopharyngeal chitini- 

 zation {hpy. ch. Plate VIII, fig. 16) (= lingua, Folsom), at en- 

 trance to pharynx, strong, triangular, considerably wider than 

 long, with tuft of long setae at each end; between tufts surface 

 covered with numerous small, irregularly arranged rugosities. 

 Coming from hypopharyngeal chitinization, creating firm support 

 for same, is the following system of five pairs of chitinous rods : 

 First pair (= lingual stalks, Folsom) (1 Plate VII, fig. 8, Plate 

 VIII, fig. 16) connecting hypopharyngeal chitinization with an- 

 terior corner of gular plate, perpendicular, parallel, imbedded in 

 membrane between articulating area of maxilla and lateral side 

 of base of mentum (or probably submental part of fused men- 

 tum — submentum). Second pair of rods (=hypoharyngeal 



