282 Transactions of the Canadian Institute. [vol. ix 



Eylais falcata Koen. 

 Syn. Eylais extendens Koenike, Abh. Nat. Ver. Bremen, 1895, XIII Bd., 

 S. 171. 



Eylais falcata Koenike, Abh. Nat. Ver. Bremen, 1897, XIV Bd., 

 S. 288. 



Female. 



The eye-capsule is 180/i. long and 125- 150^14 broad, the breadth of 

 the eye-plate 300-330/i. The anterior margin of the capsule runs more 

 or less obliquely inwards and backwards and occasionally presents a 

 slight emargination (Figs, i and 2). This species appears to vary 

 strikingly, particularly in the form of the eye-plate. The antero-internal 

 angle of the front margin of the capsule projects more or less distinctly 

 and bears here a moderately long bristle. The bridge lies a little behind 

 the level of the front margin of the capsule and is rather narrow. On 

 the front margin there is always a more or less distinct median excava- 

 tion. The opening on the under side of the capsule is usually triangular 

 though it occasionally has a rounded form ; it presents a stout marginal 

 thickening, which, beginning in front upon, or just laterad of, the side 

 of the bridge, projects behind, in some cases, over the margin of the cap- 

 sule (Fig. i). The anterior eye-lens is moderately large and mushroom- 

 shaped. The posterior lens has the usual ellipsoid form, measures 83ft 

 in length and occupies its usual position. 



The capitulum including the projecting tracheal plates is 600-700/* 

 long and 330-415/4 broad in front. The oral area is almost circular but 

 somewhat narrowed behind, i.e., short ovate; its longitudinal and trans- 

 verse axes measure i66m. Behind the oral area the maxillary shield is 

 only about 165-200/t long and is here greatly narrowed (180-2 15/1) on 

 account of the deep rounded excavation of its lateral margins. This 

 excavation appears the more pronounced, as the posterior pair of pro- 

 cesses of the maxillary shield, owing to their considerable length, project 

 conspicuously on each side. The processes appear of slenderer form in 

 lateral than in ventral view. Their free end is enlarged and bent in- 

 wards. The posterior processes of the upper wall are 215^' long, gradu- 

 ally and moderately enlarged distad to the rounded free extremity, and 

 project strongly on each side. The anterior half of that portion of the 

 maxillary shield situated behind the oral area is coarsely porous, while 

 scattered pores are distributed from the middle almost to the hind m.ar- 

 gin of the shield. 



The pharynx is only a little broader behind than in front and ex- 

 tends to a distance of 265/4 beyond the hind margin of the maxillary 

 shield. It measures 450/1 in length and its greatest breadth (behind) 

 reaches 250/4. As the breadth in front is not much less, its outline as 



