NATURAL SCIENCES OP PHILADELPHIA. 381 



cina has any hind wings or not, it is doubtful whether that species be identical 

 with dubia or with the preceding. 



Cloe mendax, n. sp. rf Pale ferruginous. Seta of antenna fuscous, pale at 

 tip. Sternum and venter pale greenish hyaline, the latter opaque at tip. Legs 

 pale, tips of tarsi cloudy. Wings hyaline, veins moderate, cross-veins fine, all 

 hyaline ; isolated veinlets all single. 



The 9 has sometimes the thorax tinged with green, and is always paler 

 above. 



Length tf 4 mill. ; $ 45 mill. Alar exp. tf 14 mill. ; O 14 m ;n. Seta 

 tf deficient; $ 9 mill. One <^; four 



The $ subimago differs in being of a uniform very pale ferruginous color. 

 The abdominal seta is pale ; and the legs are immaculate. The wings are some- 

 what opaque, and slightly tinged with dusky, as well as their veins and cross- 

 veins, and the cilia are long and dense. In the living insect the lower eyes are 

 blackish, and the upper eyes pale, and there is no intermediate seta visible. 



Length $ 4 mill. Alar exp. $ 13$ mill. Seise $ 8 mill. One tf; un- 

 known. This species differs from all the preceding, except undata, in the ter- 

 minal veinlets being single, and not in pairs. Westwood formed the species 

 having the terminal veinlets in pairs, and hind wings with only two veins, into 

 the genus Brachyphlcbia, which, however, he does not recognise in his Synopsis. 

 His definition would include C. vicina and C. unicolor, but not C. undata. (Intr. 



ir.,p. 25.) 



Cjenis. 



C^nis hilaris, Say, (:= arnica, Hagen?) I possess a single <$ subimago, 

 which agrees with Dr. Hwgen's diagnosis of arnica, except that the prothorax is 

 not banded with black like the first of his two specimens. Say states that the 

 thoracic bands of his species are also sometimes obsolete. Dr. Hagen suggests 

 that Say's species and his are identical, and it is probably the case, as Say men- 

 tions the wings being "ample," and the abdomen being " depressed," which 

 last is an unusual character in Ephemerina, and is conspicuous in my specimen. 

 The ba?al breadth of the wings is to their length as two to three, and they are 

 finely, but not densely, ciliate, and very slightly tinged with fuscous. The 

 cross-veins are only four or five, very fine and scarcely perceptible, and there 

 are no terminal veinle'.s. 



Length $ 3 mill. Alar exp. $ %\ mill. Sets deficient, except a few joints 

 of each. 



ODONATA AGRIONINA. 



N. B. It is well known that in the three tribes of Odonata Agrionina, 

 ^schnina and Libellulina, with the exception of the subtribe Gomphina, 

 where the colors are generally constant the ground colors of the body often 

 change much in drying, especially the greens and the blues, though not the 

 yellows ; that they differ much in individuals of different degrees of maturity ; 

 that they are often quite different in the two sexes, the $ frequently affecting 

 blue and the 9 green,* except in Agrion Ramburii, where it is exactly the re- 



* In Anax Junius the ground color of the abdomen of the living <J, except the first and 

 a small portion of the second segment which are grass green in both sexes as well as the 

 thorax, is invariably a vivid ultramarine blue; in the living ? it is invariably obscure pale 

 purple or lilac. Yet Say describes both sexes, of this very common insect, as of the 

 same color. iEschna constricta and clepsydra follow invariably the general rule in the 

 color of the abdomen only, d blue, $ green, thorax green d ? . In Libellulina I have 

 observed in the following species that when the d d first appear they are colored ex- 

 actly line the ? , but that they afterwards assume, sometimes over their entire bodies, a 

 milky blue tint, (bleu saupoudre,) which, as we learn from a memoir by M. Schelver, 

 quoted to me by Dr- Hagen ; is occasioned by the secretion of a kind of oil soluble in 

 ether and alcohol: Plaihemis trimaculata. Lib luctuosa, Lib. pulchella, Mesothemis Ion- 

 gipennis and Mes. simplicicollis. In Libellulina this oil, which is occasionally seen in 9 in 

 small quantities, seems to be secreted under the external integument; in Agrionina on 

 its surface, when it is known as pruinosences and may be washed off. 



1862.] 



