NATURAL SCIENCES OF PHILADELPHIA. 



401 



low, while No. 6 has a posterior yellow vitta only on its anterior femora. It is 

 unfortunate that Say in his description should have said merely " feet black- 

 ish," which decides nothing either one way or the other. Thus by the brevity 

 of the descriptions of the early naturalists, their meaning often becomes an 

 enigma, and we are reduced to guessing and dogmatizing. And yet guessing 

 is not knowing, and faith is not science. There is a profound truth contained 

 in a MS. observation of Dr. Hagen's to me : "A description of a new species 

 cannot possibly be too long ; it is always easy to curtail it, but often impossible 

 to lengthen it." 



RECAPITULATION. 



Palingenia pulchella, n. sp. 



" terminata, " 



Ephemera decora, Walk. Cat. 



" flaveola, n. sp. 



Ephemerella (n. g.) excrucians, n. sp, 



" consimilis, 



Baetisca (n. g.) obesa, Say, new imago. 

 Cloe ferrugicea, n. sp. 

 " fluctuans, " 

 " unicolor, Hagen. 



vidua, Hagen, new subimago. 



1! 



sp. 



u 

 a 



dubia, n. sp. 



u 

 u 



Perlina. 

 Pteronarcys nobilis, Hagen. 

 Acroneuria abnormis, Newm. 



" rupinsulensis, n. sp. 



Perla flavescens, n. sp. 

 " varians, " 

 " decipiens, " 

 occipitalis ? Pict. 

 producta, n. sp. 

 fumipennnis, n. sp. 

 elongata, " 



Chloroperla bilineata? Say. 



brunnipennis, n. sp. 



" nana, " 



13 sp. 

 Epbemerika. 



Rjetis femorata, Say, new imago. 

 " alternata, Say, new subimago. 

 " arida, Say, 

 " sicca, n. sp. 

 " debilis? Walk. Cat., " 

 Potamanthus cupidus, Say, new imago 



odonatus, 



Palingenia vittigera, 



limbata, Pictet. 

 bilineata, Say. 

 flavescens, n. sp. 

 interpunctata, Say, new 

 subimago. 



1862.] 27 



mendax, " 

 Csenis hilaris, Say, new subimago. 



26 sp. 



Odonata (agrionina). 



Calopteryx maculata, Beauv. 

 Hetserina rupinsulensis, n. sp. 

 Lestes rectangularis, Say. 



n. sp. 



u 



ii 



1! 

 11 



(( 

 (1 

 {( 

 (f 



11 



unguiculata, Hagen. 

 hamata, Hagen. 

 forcipata, Rambur. 

 eurina ? Say. 

 inasqualis, n. sp. 

 Agrion irene, Hagen. 



ramburii, Selys. 



exsulans, Hagen. 



putridum, Hagen. 



apicale, Say. 



civile, Hagen. 



Hagen, MS.. 



u 

 ti 

 u 

 ii 

 it 

 ii 

 a 



n. 



binotatum 



P- 



16 sp. 



Odonata (^Eschnina.) 

 Herpetogomphus rupinsulensis, n. sp. 

 Macrogomphus spiniceps, 

 Gomphus spinosus, Selys. 



" fraternus, Say. 



" vastus, Hagen MS., 



" graslinellus, n. sp. 



" fluvialis, " 



" amnicola, 

 Cordulegaster obliquus, Say. 

 Anax Junius, Drury. 

 iEschna clepsydra, Say. 



" constricta, Say. 



n. sp. 



