264 EEV. A. E. EATON ON EECENT EPHEMEEID.^ OR MAYFLIES. 



upper side {i. e. the side farthest from the auricle of the pergamentose lamina). Median 

 caudal seta about If as long as the others, and twice as long as the body ; their joinings 

 beset with minute spreading hair. Pronotura transverse, imperfectly delimited, being 

 confluent with the mesonotum at the lateral margins (although well defined elsewhere) 

 and there slightly dilated anteriorly. Ventral segments short, the lobe of the 9th in 

 the ? triangular ; pleurae in segments G-9 produced posteriorly into short acuminate 

 triangular teeth. Fangs of the mandibles slender, compressed, subequal in length ; the 

 exterior 2-3 denticulate at the tip, and serrulate at the upper border ; the inferior fang 

 bidendate in the right mandible, tridentate in the left, without remarkable differences in 

 the teeth. Maxilla i. and tongue very similar to those of Nymph No. I. ; the former 

 more sparsely beset with spinules and cilia?, in the place of pectinate teeth, at the edge 

 of the crown, and with stronger fangs at the point ; its palpus furnished with a com- 

 pressed acute spine below its pimgent point. Femora marked on the coloured side with 

 two broad dark bands, each containing a pale blotcli upon the upper margin ; the bands 

 are confluent below. Length of body 7"2, setae 13 mm. 



Sab. The Falls of Niagara, N. Y., 3 examples by Mr. H. Hubbard, 22, v. 1874 (Mus. 

 Comp. Zool. Cambridge, Mass.) ; also 3 or 13 probably from Ithaca, Fall Creek, N. Y., 

 and G from Crystal Lake by Prof. S. A. Forbes. Figured and described from specimens 

 communicated by Dr. Hagen. 



Nymph, No. III.— PI. LIX. (whole figure and details). 



Abdominal tracheal branchioB all reclinate at the sides of the body, with moderately 

 long fascicled fibrils ; laminae oblique, the foremost and the hindei*most two obtuse and 

 almost semi-obovate, the others subovate, triangular, and broad ; branchial trachea3 well 

 developed, arborescently branched, excentric, with their longer branches ascending or 

 directed towards the broader sides of the laminas. Caudal setae defective in the specimens 

 examined ; the median seta Avell develojjcd. Pronotum transverse, very short, well 

 defined behind ; the lateral margins dilated and rounded off. Ventral segments subequal 

 in length ; the lobe of the ninth segment of the ? narrowly elliptical at the tip ; pleurae 

 in segments G-8 produced into minute acuminate teeth. Fangs of the mandibles slender, 

 unequal, stronger in the left than in the right mandible ; the exterior fang, bifid, and 

 denticulate along its upper side in the latter, is in the former more compressed, acumi- 

 nately lanceolate, and serrulate along both edges; tbe interior fang, slightly bifid, or 

 slenderly bidentate in both of them, is in the right mandible obviously stunted, and in 

 place of an endopodite has three short unilaterally plumose setulse, Avhile the other 

 mandible has only a single smooth setala in that place. Lacinia of maxilla i. beset at 

 the edge of the crown with numerous flattened pectinate teeth, and with a few bristles 

 at the point instead of spines ; proximal joint of the palpus stout ; terminal joint slen- 

 derly clavate, obliquely trimcate, densely puljesceut at the end and acute at the tip. 

 Tongue very similar in form to those of the preceding two nymphs. Femora marked on 

 the coloured side with three irregular zigzag grey fasciae, narrowly confluent in the 

 n\iddle, preceded by a solitary oval spot near the base. Length of body 7 mm. 



