270 Scientific Proceedings^ Royal Dublin Society. 



has observed a female of H. Uneatum to lay 538 eggs- in forty-eight minutes on 

 a calf confined for experiment. The ovarioles open, singly or by twos, threes, 

 or fours, into what may be termed " secondary ovarian tubes," which join 

 together to form larger tubes ; ultimately, about five or six main ovarian 

 tubes unite to form an oviduct. This arrangement of the ovarioles gives to 

 the ovary a cliaracteristic tufted appearance, which resembles tliat of tlie ovaries 

 of Beetles ratlier than of other nearly related Diptera in wliich the fine ends 

 of the ovarioles are continued into converging threads attached, as described 

 by Lovvne ('95, p. 668) for the Blow-fly Calliphora, to the dorsal wall of a 

 common ovarian sac. In the Crane-fly (Tipula), however, and in other more 

 primitive Diptera, as described by Dufour ('51), a number of ovarioles open 

 independently into a central cliamber continuous with the oviduct. 



The egg in the ovariole is already surrounded by the well-known shell 

 with its grooved, flange-like process for attachment to the host-animal's hair. 

 Throughout its progress from the ovariole to the vulva the egg moves with 

 this process in advance. The right and left oviducts (fig. 1, od.), leading 

 respectively from the two ovaries, unite to form a common oviduct (od.'), 

 which merges into the vagina (fig. 1, va.) ; the latter opens at the end of the 

 ovipositor behind tlie eighth abdominal segment. We can find no sacculus 

 or copulatory vesicles such as are described and figured from the House-fly 

 (Musca) by Gordon Hewitt ('07, pp. 430-1). The common oviduct and 

 vagina form a sub-eylindrioal tube nearly filling the cavity of the elongate 

 terminal abdominal region, which is modified into the ovipositor. With the 

 ovipositor extended, no more than the ovaries can remain in the general 

 abdominal cavity. 



2. Accessory Gj.ands anb SpekmathecjE. 



Into the proximal end of tlie vagina open dorsally the ducts of the two 

 elongate tubular accessory glands (" parovaria " of Lowne) and of the three 

 spermathecse. The accessory glands (Plate XXI, fig. 1, and Plate XXII, 

 fig. 4, a.g.) have the walls composed of granular cells with a delicate fibrous 

 sheath ; their ducts (fig. 4, d.'), which are lined with ehitin and have a thick 

 muscular wall composed of fibres arranged circularly, open into the dorsal 

 wall of the vagina slightly in front and on either side of the openings of the 

 spermathecal ducts. 



The spermathecce (figs. 1, 4, sp.) are three dark brown ovoid chitin-lined 

 capsules, each with a duct, also chitin-lined ; the ducts opening close together 

 in the mid-dorsal region of the vagina (fig. 4, d.). In the terminal portion of 

 eacli duet, the wall is dilated ; for the remainder of its course each duct is 



