44 



Bin.LETIN 00, UNTTED STATER NATIONAL MUSETTM. 



gToiind); composed of 14 full}- calcified plates separated b\' linear 

 sutures. The plates are sculptured with growth-lines and some fine, 

 indistinct radial stripe. The cuticle is thin and inconspicuous, nearl}' 

 smooth except on the keel, where the roof is finely and shortly pilose, 

 and crossed 1)}" six to eig-ht transverse tufts of longer hairs. 



The scutimi is about twice as long as wide, its occludent margin 

 ver}^ slightly convex. The lateral margin is concave near the tergo- 

 lateral angle, elsewhere convex. Basal margin straight. The umbo 

 is nearl}' terminal, bent inward, with a very small triangular area 

 outside and extending slightly above it, at least in old individuals. 



The tergum is much longer than the scutum, triangular. Its occlu- 

 dent margin is nearly straight, l)ut recedes siightl}' near the erect 

 apex. Scutal margin is straight. The carinal margin has a slight 



prominence just aV)ov(^ the sum- 

 mit of the carina. 



The carina is moderately 

 arched, and extends a shori dis- 

 tance ahove the jprominent umho. 

 Its upper end is rounded, and 

 not in the least interposed be- 

 tween the scuta. The roof is 

 nearly flat, bounded by distinct 

 ])ut obtuse angles. A low rib 

 runs on each side parallel to and 

 near the angles. The lines of 

 growth on the roof are deeply 

 arched downward. The sides 

 are flat and very wide in the up- 

 per half, delicately sculptured 

 with fine longitudinal and radial 



FIK.13.-SCALPELLUMAEIETINUM. a, LATERAL VTKW, ^^j.iy,_ ^\^q \)^q^\ margin IS 



3: /), DORSAL VIEW -1. - . 



deeply rounded. 1 here is no 

 chitinous space between the carina and the other plates. 



The upper latus is pentagonal, the scutal and carinal margins about 

 equal and parallel, the tergal margin a trifle longer. The basal mar- 

 gin is shorter, and the oblique margin against the inf ramedian plate is 

 still shorter. The umbo is not quite apical, the apex beyond it being 

 obtuse, rounded, and white. 



The rostrum is quite small and triangular, with equal sides. 



The rostral latus is low, about five times as long as high, and some- 

 what narrower in front than at the lateral end. It stands out in relief 

 above the surface of the scutum. 



The inf ramedian latus is irregular!}^ pentagonal, al)Out twice as high 

 as wide. It has a short, straight margin against the lateral edge of 

 the scutum, a longer straight one against the U4:)per latus, about as long 



