A COXTRIBUTIOX TO THE LoWER DEVONIAN FaUNAS OF MARYLAND 51) 



Description. — '"General form and projiortions. Body subelliptical in 

 outline, more or less produced at the extremities. Surface depressed con- 

 vex, distinctly trilobate; lateral margins deflected and subparallel. 

 Length (including caudal spine) to width as 2 to 1. Cephalon relatively 

 short, length about one-third the width; outline crescentic, slightly pro- 

 duced on the frontal margin. Surface evenly convex. Border narrow 

 anteriorly, bearing in front of the glabella five to seven low crenulations 

 or undulations, which become wider and thicker upon the cheeks, and 

 produced at the genal angles into stout and rapidly tapering spines, which 

 reach the third thoracic segment. Doublure wide and deep at the genal 

 angles, narrowing at the lateral margins, and extending into a relatively 

 narrow epistoma in front. Facial sutures normal. 



" Glabella elongate, subpentagonal, widest anteriorly, depressed convex ; 

 bounded on all sides by low sulci. Anterior lobe large, subrhomboidal ; 

 first pair of lateral furrows long, inclined backward; second pair obsolete, 

 except at their proximal extremities, where they appear upon the cast as 

 two deep pits; third pair transverse or inclined slightly forward, almost 

 obsolete at their distal extremities; first and second glabellar lobes coa- 

 lescent, forming a single pair of large convex lobes, whose elevation ex- 

 ceeds that of the frontal lobe; third glabellar lobes narrow, depressed and 

 relatively inconspicuous. Occipital furrow narrow on the axis, becoming 

 broader and deeper on the cheeks, occipital ring prominent and bearing 

 short and sharp central spine, narrowing to the axial furrows, thence 

 rapidly widening to the genal spines. 



" Eyes lunate, large and elevated considerably above the summit of 

 the glabella, and closely appressed against its coalescent first and second 

 lobes. Visual surface with numerous corneal lenses, the single specimen 

 (a young individual) in which they may be enumerated, showing eighteen 

 rows, counting diagonally from the lower posterior margin, and one 

 hundred and ninety-two lenses. Palpebrum scarcely prominent; palpe- 

 bral lobe depressed and sloping abruptly to the narrow and elevated 

 palpebral furrow. Cheeks sloping abruptly from the ocular node to the 

 thickened and somewhat flattened margin. A deep sinus which is 



