CRUSTACEA. 
135 
Phaethonides vaeicella, n. sp. 
PLATE XXIV, FIGS. 29-31. 
Cephalon. Intra-sutural portion only observed. Outline sub-circular. Frontal 
area broad, concave, strongly recurved at the margin. Margin slightly 
thickened by doublure, elevated, reaching or exceeding the height of the 
glabella. Palpebral lobes conspicuous. 
Facial Sutures normal. 
Glabella elongate-ovate or pyriform, bounded by a low sulcus; convex, 
slightly flattened above. Basal lobes strong; baso-lateral furrows broad and 
deep; antero-lateral impressions duplicate, very faint upon the crust but 
apparent upon the lower surface. 
Thoeax not observed. 
Pygidium broad, the outline being the arc of a circle whose center is the middle 
of the first annulation. 
Axis elevated, relatively narrow and longitudinally arched, abruptly ter¬ 
minating before reaching the posterior border; composed of eleven or twelve 
transverse annulations. 
Pleurae broad, depressed-convex, flattened at the margin, which is strongly 
thickened by doublure. Pleural annulations eight, six of which are sulcate 
and double. The cast of the lower surface, which serves the purposes of 
description, shows the last two annulations more distinctly than they would 
probably appear upon the upper surface of the test. 
Surface of the cephalon ornamented by tubercles, which are scattered over 
the glabella, and are stronger upon the adjoining frontal and lateral areas. 
Upon the recurved marginal area the ornamentation changes to strong, abun¬ 
dant punctse, which become finer toward the margin itself On casts of the 
lower surface this punctate structure is to a large degree lost. The pygidium 
bears an axial row of bead-like tubercles with two less conspicuous rows on 
each side. The pleurae show traces of three or four rows of tubercles, which 
become obsolete toward the posterior extremity. 
