EPHEMERINA. 
333 
and behind is a broad, sternal, large area, broader and shorter than in 
Agrion. 
It should be observed that in Odouata the middle and hind legs are 
close together. 
THE ABDOMEN. 
In Agrion (PI. L, tigs. 4-6) there are ten uromeres. The first tergite is 
veil-developed, the second one-half as long as the five succeeding tergites. 
No pleurites, the tergites overlapping the urosternites, which are very 
narrow. The tenth urosoine shorter than broad. The claspers possibly 
represent an eleventh urosoine, as such a segment is developed in the 
embryo, but in the adult the claspers appear to be appendages (cer- 
copoda) of the tenth urosoine. Calopteryx closely resembles Agrion as 
to its abdomen. 
In HSschua (PI. XLIX, L. figs. 1-3) there are ten uromeres; and the 
rudiments of an eleventh urosternite; the cercopoda (c) are loug and 
spatulate. 
Suborder 3 EPHEMERINA. Plates XLV, XLYI. 
THE HEAD. 
Ephemera .— It has been difficult with the material at my command to 
properly describe the external anatomy of any member of this group. 
The species examined was our commonest Ephemera in Rhode Island, 
identified by Dr. Hagen as probably E. cupida (Leptophlebia) Walk., 
and also aspecies of Palingenia. There is a great deal of variation in 
the form of the thorax and head in the genera of this suborder, which 
is as much specialized in its way as the Odouata is in its. 
In examining the under side of the head of an alcoholic Ephemera, 
the subject of the drawing made by Dr. Gissler (Fig. 2), there is a cav- 
ernous area, at the bottom of which I can discover what appear to be 
the rudiments of the maxillae and labium. There are certainly no rudi- 
ments of the mandibles. The gular region and the ineutum can be dis- 
tinguished, and I think I can detect the labial palpi and lingua; con- 
cerning the maxillm I am less certain. The drawing was made by Dr. 
Gissler from but one specimen, and while correct in most respects he 
regards the sketch of the mouth-parts as provisional. The general 
relations of the under side of the head are as he drew them, with one or 
two corrections made by the writer. 
In an alcoholic specimen of Palingenia, hilineata (perhaps a subimago) 
I can discover no certain rudiments of any of the mouth-parts. The 
under side of the head forms a deep hollow, and the mouth region is a 
deep pit, bounded by a high, thin wall in front — the lower edge of the 
clypeus. This pit is open to the roof of the mouth or clypeus. It is 
impossible to distinguish the rudiments of any of the mouth parts, and 
practically they appear to be wholly obsolete. 
