208 PALEOZOIC PALEONTOLOGY. 
PTERYGOMETOPUS INTERMEDIuUS (Walcott). ? 
Plate XV., Fig. 33. 
1879. Dalmanites intermedius Walcott, 31st Rep. N. Y. State Mus. 
Nat. Hist., p. 69 (p. 16 of adv. sheets, 1877). 
1897. Pterygometopus intermedius Clarke, Pal. Minn., pt. I1., p. 727, 
figs. 45-47. 
In some of the lower beds of the Jacksonburg section, below those 
containing P. callicephalus, the pygidium of another species of Ptery- 
gometopus sometimes occurs. These pygidia are longer and much 
more triangular in outline than those of P. callicephalus and are 
usually smaller. The sides of the axis are slightly concave inward, 
giving it a slightly constricted appearance near the centre of its 
length. The axis extends nearly to the posterior extremity of the 
pygidium, is rounded at its end, and has about twelve annulations, 
with sometimes faint traces of several additional ones. The plure 
slope away abruptly from the axis, especially posteriorly, and are 
marked by eight ribs, the first two or three of which are usually 
slightly grooved. 
The head of this species has not been observed, so that it cannot 
be identified with certainty as P. intermedius, but the characters of 
the pygidium approach more closely to that species than to any other. 
OSTRACODA. 
LEPERDITIA FABULITES (Con.). 
Plate XIII., Figs. 11-12. 
1843. Oytherina fabulites Conrad, Proc. Acad. Nat. Sci. Phil., vol. 
ip oox. 
1897. Leperditia fabulites Ulrich, Pal. Minn., pt. IL, p. 634, pl. 43, 
figs. 10-14. 
“Carapace of medium size, obliquely subovate, comparatively long, 
widest posteriorly; ventral curves moderate, strongest just behind 
the midlength; cardinal line straight, comparing with the length 
