infesting the common Howe-Fly in Bombay. 31 



posterior end of the hepatic organ (m), where it again appears 

 to bifurcate, and to embrace the intestinal sheath. 



Generative organs situated in the anterior part of the body, 

 under the CEsophagus and anterior part of the intestine, con- 

 sisting of an ovary (fig. 3/) and testicle [h), opening on the 

 right side, a little in front of the liver, by separate ducts about 

 one-hundredth of an inch apart, — the former, which is anterior, 

 by a simple papillary aperture {g), and the latter by the same, 

 but with a short funnel-shaped exsertile organ [i). Ovary un- 

 seen in detail, but charged with nucleated cells, and presenting a 

 distinct line of demarcation between itself and the testicle, which 

 on its part appears to be saccular, and also contains nucleated 

 cells that are sometimes spermatophorous (fig. 4). Spermatozoa 

 indistinctly seen ; single, in cells about 1 -700th of an inch in 

 diameter; consisting, when half-developed, of a striated, pyra- 

 midal or triangular body growing out of a small mass of gra- 

 nular mucus on one side of the cell (a, b) ) when fully developed, 

 apparently club-shaped (c). 



Size. About 1-llth of an inch long and l-313th of an inch 

 in its broadest diameter, that is, in the middle. 



Hab. Proboscis, head, and posterior part of the abdomen of 

 the common House-fly {Musca domestica). 



Lac. Island of Bombay. 



Observations. — The papilliferous head, transversely striated 

 body, and general form of this worm ally it more to Filaria 

 medinensis and the microscopic free Filaridse which I have de- 

 scribed under the generic term of " Urolabes*," than to any 

 other of the Nematoid families; but, of course, the characteristic 

 penis of the Filaridse, both in form and position, is here absent, 

 from the approximation of the male and female outlets of the 

 organs of generation, which seems to be entailed by the bisexu- 

 ality (although it is not by any means apparent why it is the 

 male organ which should be transposed), while the latter still 

 maintains its posterior position with respect to the former. The 

 advancement of the vulva towards the head is not remarkable, 

 for in Filaria Equi it is close to the anterior extremity f. The 

 spermatozoon, however, more nearly resembles that of Ascaris 

 mystax, both in form and development J. The inflated spinife- 

 rous extremity of the tail of F. Musca, besides being more cha- 

 racteristic of the male than the female, whose tail in the Filaridae 

 generally is whip-like, has its resemblance in one of the free 

 microscopic species which inhabit the salt-water drain of the 

 town of Bombay, with this difi'erence only, that the spines of 



• Ann. Nat. Hist. ser. 3. vol. iv. p. 28, July 1859. 



t Blanchard, Ann. des Sc. Nat. 3 s^r. t. 2U. pi. 6. fig. 3 a. 



X Phil. Trans. 1852, pi. 26. 



