42 THOMAS SAY FOUNDATION 
side of the prothorax. The head is very thick and the maxillae are 
very large, bulging out each side of the head so as to be visible 
from above. General color yellowish brown with yellow markings. 
Three ocelli placed in a triangle of which the base is longer than 
the sides; eyes medium in size; a more or less plain occipital 
ridge is noticeable, composed largely of short stout brown hairs; 
epicranial suture distinct. 
Pronotum narrower than head, wider than long, with broadly 
rounded angles; surface of pronotum somewhat rugulose ; meso- 
and metanotum marked similarly to pronotum ; wing pads almost 
parallel to body; legs with a fringe of long fine hairs on the 
femora and the tibiae; first and second tarsal segments very short, 
subequal ; one and two together not over a fourth as long as third. 
Abdomen slightly flattened; tenth tergite triangularly pro- 
duced ; cerci more than a third as long as the body, with a fringe 
of hairs on the dorsal surface, and each segment ending in a 
whorl of short hairs. 
The mouth parts are of the typical carnivorous type, the most 
conspicuous feature in which they differ from other genera of 
the Perlidae being the structure of the maxillae and labium. 
Labrum about three times as wide as long, anterior margin 
with long hairs, and with many others on the ventral surface. 
Mandibles slightly asymmetrical, each mandible having five or 
six teeth, placed in two groups, one of three, and the other of 
three or two. Following the teeth there is a fringe of hairs on 
the inner margin, and also a row of hairs on the ventral surface 
and one on the dorsal surface. 
Maxillae very large; lacinia wide at base and bidentate, with 
the second tooth not much more than half as long as the apical 
one; galea slender and eylindric, with a small, membranous, at- 
tenuated, spinulose tip; palpus five-segmented; cardo and stipes 
very large and massive. 
Labium: glossae small and rounded; paraglossae large, pear- 
shaped, and directed inward, with a membranous spinulose tip ; 
mentum a narrow transverse band; submentum large and bearing 
at each outer, basal corner a small single gill; hypopharynx 
broadly rounded, and at the apex closely beset with fine bristle- 
like hairs. 
Nothing is known about the biology of this genus. No specimens 
have been reared, and identification of the species treated in this 
paper was made possible by studying the genital structures in 
mature nymphs. The structure of the nymphs would indicate 
