402 



LECTURE XVIII. 



In most Diptera the ovaria consist of numerous short egg-tubes, 

 each divided into three or four compartments : the egg-tubes are va- 

 riously disposed, combined, and associated in the different species : 

 in Ephydra and Tachina they are long enough to contain about 

 twenty egg-chambers. The sperm-reservoir is present ; it is gene- 

 rally trifid, rarely bifid, as e. g. in the Stomoxis, still more rarely 

 simple, as in Pulex. The colleteria consist of two simple, rarely, as 

 in the TipulidcB, ramose tubes ; which, in the latter, furnish a con- 

 siderable quantity of albuminous matter, binding the eggs together 

 in filamentary forms, when they are committed to the waters. 



There is no bursa copiilatrix ; but beneath the sperm reservoir, 

 in the common fly, the vagina swells out into a cordiform cavity, 

 which receives the impregnated ova, and in which they are developed 

 in the larviparous genera, e. g., 3Iusca, Anthomyia, Sarcophaga, 

 Sachina, and Dexia. 



In the forest-fly (Ilippobosca), the ovaria are each a small simple 

 cjEcum, opening into a short common oviduct, which swells out 

 a little above the communication. A pair of small sperm-reser- 

 voirs next open into the oviduct, and afterwards the ducts of two 

 voluminous ramified colleteria ; the part answering to vagina, swells 

 out below this into a uterus, in which the ova are developed, and the 

 larva metamorphosed, in this pupiparous insect. 



In most Lepidoptera, the ovaria consist of four pairs of egg-tubes, 

 disposed as I have already described. The sperm-reservoir {Jig> 158, 

 b) is pyriform, and generally provided 

 with a long spiral ductus seminalis, 

 in whose basis a sometimes simple, 

 sometimes bifurcate glandular csecum 

 opens. The colleteria {e) are situated 

 below, and consist of a pair of convo- 

 luted casca, swelling out into pyriform 

 receptacles at the vagina, where they 

 open by a common duct. 



In some butterflies, two small 

 branched glandular organs are super- 

 added, called the " scent-glands" (c) ; 

 they secrete the peculiar odorous particles that attract the males ; 

 and of which property the entomologist sometimes avails himself in 

 catching the finest specimens of that sex. 



The bursa copulatrix (/) finally presents a remarkable develop- 

 ment, being a capacious pyriform, sometimes hour-glass-shaped, 

 reservoir, which is furnished with a peculiar, intussusceptive canal 



158 



Noctua Brassicae. 



