22 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
BUMASTUS GRAFTONENSIS Meek and Worthen. 
Illaenus (Bumastus) graftonensis Meek and Worthen, Proc. Acad. nat. sci. 
Phil., 1870, p. 54; Geol. surv. Illinois, 1875, 6, p. 508, pl. 25, f. 4. 
Bumastus sp. ind. Meek and Worthen, Geol. surv. Illinois, 1875, 6, pl. 24, f. 3. 
Illaenus graftonensis Weller, Bull. Chicago acad. sci., 1907, no. 4, pt. 2, p. 223, 
pl. 16, f. 4-6. 
Only the cephalon of this species has previously been known, but 
the Day collection contains two complete, though somewhat flattened 
specimens from Waukesha, Wisconsin, where this species seems to be 
fairly common. 
The cephalon is too well known to need further description, except 
to note that as in B. iorus, there is a prominent median tubercle be- 
tween the eyes and near the posterior margin. 
The thorax has ten segments, a broad axial lobe, rather well-defined 
dorsal furrows. The pleura of the thoracic segments are more promi- 
nent and ridged, and not so flat as in most species of Bumastus. The 
pygidium is short and moderately convex, with a flattening around 
the margin, but not a real concave border. The pygidium resembles 
that of B. ioxus, but is shorter-and wider, the average ratio of length 
to width in B. zoxus being .64 and in the two pygidia of B. graftonensis 
which we have, .54. 
Formation and locality: — Nine specimens (M. C. Z. coll.) are from 
the Niagaran at Waukesha, Wisc., a locality from which this species 
has not previously been reported. 
BUMASTUS INDETERMINATUS (Walcott). 
Plate 2. 
Illaenus indeterminatus Walcott, 31st Ann. rept. N. Y. state mus. nat. hist., 
1877, p. 19 adv. sheets; 31st Ann. rept. N. Y. state mus. nat. hist., 1879, 
p. 70. 
Illaenus cf. I. indeterminatus Clarke, Pal. Minn., 1897, 3, pt. 2, p. 716, f. 24. 
Bumastus indeterminatus Raymond and Narraway, Ann. Carnegie mus., 1908, 
4, p. 253, pl. 62, f. 8, 9. 
The M. C. Z. contains the type of this species, and it is figured 
(Plate 2) for the first time. The specimen consists of a good cephalon, 
part of one free cheek, a very much dislocated thorax, of which only 
seven segments can be definitely made out, and a very fine pygidium. 
