496 Systematic Paleontology 



HOMALONOTUS VAXUXE.MI Hall 



Plate LXXXIX, Figs. 13-15; Plate XC, Fig. 3 



Homalonotus vanuxemi Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 352, pi. 



Ixxiii, figs. 9-14, 1861. 

 Homalonotus vanuxemi Hall and Clarke, 1888, ibidem, vol. vii, p. 11, pi. vb. 



figs. 1, 2. 

 Homalonotus vanuxemi Weller, 1903, Pal. N. J., vol. iii, p. 321, pi. xxxix, figs. 



7, 8; p. 338, pi. xliv, figs. 4-7. 



Description. — " Thorax long : sides subparallel, the middle lobe flat- 

 tened on the exterior surface ; articulations arching forward ; longitudinal 

 furrows faintly defined, being a simple undulation in the articulations; 

 lateral lobes narrow, the articulations bent abruptly downwards at the 

 sides. Pygidium subtriangular with the articulating side much longer 

 and broadly curving, extremely convex: axis prominent in the young 

 specimens, and becoming subdued in older ones; width, at its upper ex- 

 tremity, equal to that of each of the lateral lobes, xlnnulations fourteen 

 or fifteen in the cast, and twelve ribs visible on each of the lateral lobes. 

 Surface of the test punctate and striato-punctate : cast punctate." Hall, 

 1859. 



Cephalon convex depressed, having the shape of a flaring U, lateral lines 

 rectilinear, making with each other an angle of about 54°, anterior margin 

 somewhat broadly rounded. Length to width about as 2 to 3 ; genal angles 

 rather abruptly but regularly rounded. Facial sutures originating in 

 genal angle nearer the lateral margin, thence running obliquely forward, 

 rounding and passing inward parallel to posterior margin of cephalon 

 toward points posterior to the eyes, thence again obliquely inward to the 

 eyes, thence forward to anterior margin. No transverse suture observed, 

 but may be present. 



Glabella subescutchenoid, broader posteriorly, lateral margins almost 

 rectilinear, but slightly concave outwards, anterior angles rounded, pos- 

 terior angles sharp, length five-eighths, or less, that of the cephalon, 

 lateral furrows undefined in specimens observed. Cheeks free, sinuous 

 on surface and abruptly deflected marginally. Eyes situated on large 

 elevated protuberances which are slightly elliptical parallel to the 

 lateral margin of the cephalon and each bounded by a wide shallow furrow 

 which is less definite adjacent to lateral margin of the cephalon. Visual 



