NEUROPTERA.—PERLIDE. 21 

the other parts of the mouth. The body is oblong, depressed, and of 
equal breadth throughout, the head (_fig.60.3.under side ) being flat, as 
broad or broader than the prothorax, which is large, flat, and quadrate; 
the eyes prominent, semiglobose, and lateral ; the ocelli three, in a tri- 
angle, between the eyes ; the antenne nearly as long as the body, and 
multiarticulate ; the basal joint being largest, and the third and following 
exceedingly short ; the upper lip is transverse, and very short; the man- 
dibles in Perla are small, flat, and membranous ( fig. 60. 4.). In a beauti- 
ful Australian species, they are horny and toothed (fig. 60.15.), whence 
Ihave formed this insect into a distinct genus, Eusthenia spectabilis 
Westw. ( Griffith, An. Kingd.) ; in Nemoura they are also horny, and 
armed with several teeth ; the maxillee are widely apart, with a long 
basal articulation, and two short and slender terminal lobes ; the max- 
illary palpi are slender, and 5-jointed (fig. 60. 5.) ; the mentum ( fig. 
60.6.) is large, covering the greater part of the under side of the 
head ; the labium is smaller and quadrate, deeply slit down the middle ; 
the lingua (overlooked by Curtis) being well developed, not slit, and 
occupying its internal face ; the labial palpi are 3-jointed ; the three 
thoracic segments are nearly equally developed; the abdomen is 
sessile, soft, depressed, of equal breadth, 9-jointed, and in the large 
species furnished with two long and slender articulated filaments ; the 
wings are longer than the abdomen, upon which they are horizontally 
extended at rest, the posterior pair being the largest, and folded; the 
legs are of moderate length, compressed, and simple; the tibial spurs 
very short ; the third or terminal joint of the tarsi is larger than the 
two preceding united in Perla (fig. 60. 7.) ; but in Nemoura the joints 
are of equal length. There is a very great diversity in the sexes of 
the typical genus Perla, the males being much smaller than the fe- 
males, with very short wings (Curtis and Lucas, in Ann. Se. Nat., 
c 3 
