INSECTA. 491 
an efferent canal arising from two small vesicles filled with a yellow 
fluid : these glands are wanting in Agrion’. The larvee and nymphs 
live in the water, and resemble the perfect insects. The under-lip 
has the form of a mask or hood, and covers the mouth ; anteriorly it 
terminates in two hooks*®. It is bent round and set upon a long 
flat pedicle, which the animal can move forward rapidly, whereon 
the bending disappears ; thus the insect supplies itself with a move- 
able forceps for seizing its prey unawares at a distance with the 
hooks at the extremity of the under-lip. (See figures in SwAMMER- 
DAM, Bibl. nat. Tab, xu. fig. 5, Réaumur, Ins. vi. Pl. 36, fig. 4m, 
figs. 10—14, Pl. 37, figs. 4, 6, 7, Pl. 38, figs. 6—8, Rasen, Jns. 11, 
Ins. aquat. Cl. II. Tab. 11. figs. 70, fig. 8c, Tab. 1x. figs. 3,4; Lyonet, 
Quvr. posthume, Pl. 18, figs. 13—15). The abdomen of the larva 
ends either with five horny plates, which can be moved from and to 
each other, or with three fin-like lamine ; it was in these lamine 
(in the genus Agrion) that Carus first discovered the circulation of 
the blood ; see above, p. 259. 
With Linyavs this family forms only a single genus, Libellula. 
Comp. on this family VAN DER LinDEN, Agriones Bononienses descripte. 
Opuscoli scientifict. Bologna, 1823, Tom, Iv. p. tor; ejusd. Ashnee Bononi- 
enses, ibid. p. 158, &c.; ejusd. Monographie Libellulinarum Europearum 
specumen. Bruxellis, 1825; Toussaint DE CHARPENTIER, Libelluline 
Europee descripte et depicte, cum Tabulis 48 color, Lipsiz 1840, 4to; 
E. DE SeLtys Lonecuamps, Monographie des Libellulines d’ Europe, Paris 
et Bruxelles. 1840, 8vo; and the same author’s different short communi- 
cations in the 6th and 7th parts of the Bulletins de U Acad. des Sc. de 
Bruaelles. 
A. Intermediate lobe of labium very small, lateral lobes very 
broad, without articulate style. 
Lribellula Fase. Eyes large, often contiguous. Oceili disposed 
in a triangle. Wings horizontal, expanded, anterior different from 
1 Fuller information concerning these parts may be found in H. RatuKer, De 
Libellularum partibus genitalibus, Cum Tab. en. 111. Regiomonti, 1832. 4to. Because 
the penis is not connected with the testes, of which the vasa deferentia terminate at the 
ninth ring of the abdomen, RATHKE was of opinion that the union observed in the 
Libelluline is not a true copulation, but only precedes it. Von SrmBoxpD, however, 
detected spermatozoa in the male at the base of the abdomen, so that the male, by 
bending round the abdomen towards the thorax previous to copulation, seems to deposit 
the sperma there. WIEGMANN’s Archiv f. Naturgesch. 1838, p. 375. 
2 These nippers are the palpi of the under-lip ; see A. BRULLS, Observations sur 
la bouche des Libellulines, Ann. de la Soc. Entomol. 11. 1833, pp. 343—351, Pl. 13. 
