Eusarcus longiceps nov. 
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1 Carapace of young specimen showing outline and position of lateral eyes. 
Natural size 
2 Carapace of young specimen with traces of ornamentation 
Well preserved specimen, showing marginal border and outline of ventral 
side (as darker rim). Probably somewhat compressed in posterior 
part. Natural size 
4 Largest carapace observed. The lateral margin is partly folded under 
and the specimen appears therefore too narrow. The lateral eyes 
and ocelli are well preserved in the specimen; the former are some- 
what displaced by the folding. Natural size 
5 Carapace and preabdomen; the former apparently retaining the original 
outline. Type. The preabdomen is imperfect. Natural size 
6 Large carapace with the marginal shield of the ventral side thrown 
outward in the posterior part. Natural size 
(ON) 
Eusarcus triangulatus nov. 
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7 Largest and most perfect carapace observed, apparently but little dis- 
torted and-retaining the first tergite. Type. Natural size 
8 Small carapace with fragment of first tergite. x 2 
g Carapace and preabdomen much distorted, but showing their great width. 
The swimming leg is too indistinct for accurate figuring. Natural size 
Disjecta membra referable to Eusarcus 
1o Metastoma, possibly belonging to Eusarcus longiceps. x 2 
11, 12 Metastomas, possibly belonging to Eusarcus triangulatus. 
Natural size 
13-16 Patches of integument exquisitely retaining the ornamentation. 
The latter exhibits considerable variation, recalling the ornamen- 
tation of Eusarcus and Echinognathus. Figure 13, x 4; figure 14, 
x 5; figure 15, x 2; figure 16, X 5 
17 Portion of abdomen, comparable in outline to that of a Eusarcus. 
Natural size 
18 Postabdominal segment, recalling that of a Eusarcus. Natural size 
I9, 20 Spines of endognathites, belonging to this genus, or to Echino- 
enathus or Stylonurus. Natural size 
Hortzon and locality. Lower Siluric: Schenectady shale. The originals 
of figures 1-7, 10, I1, 13-16, 18-20 are from the Dettbarn quarry at 
Schenectady, those of figures 8, 9 from Duanesburg, that of figure 12 
from Rotterdam Junction and that of figure 17 from Aqueduct, ail 
in Schenectady county. All originals are in the State Museum 
608 
