234 THE MALE GENERATIVE ORGANS 



and is armed with strong spines, which are thickened at the base 

 and tapering towards the end. The posterior is a fac-simile of the 

 anterior. On each end we get a protuberance or crown. When 

 the anterior crown is flattened by pressure — as, for example, by 

 the cover-glass — we find a circular orifice, or stoma, whose dia- 

 meter is the one-two-thousandth of an inch {Fig. 3). It is com- 

 posed of eleven segments or petals These petals, in their natural 

 position, seem to perform the office of valves. This orifice is the 

 commencement of the vas deferens, which lines the interior of the 

 mucous gland, and, passing out at the posterior of the same, con- 

 tinues its course for a short distance in a straight line, and then 

 takes on a spiral form,* whose end straightens out and enters the 

 bursa copulatrix by the ligamentous tissue that binds the bursse 

 together at their lower extremity. 



The bursa copulatrix in Cypris cinerea is a clasper- or pincer- 

 like arrangement ; the chelate ends resemble the claws of the 

 first pair of the thoracic members of the lobster (Fig. i). It is 

 situated in front of the post-abdominal rami, and, like the mucous 

 glands, lies in apposition, with its chelate ends pointing towards 

 the posterior portion of the body of the creature. It is com- 

 posed of chitine, and resists the action of liquor potassse, yet the 

 alkali differentiates its structure and facilitates the tracino; of the 

 intromittent organ. 



The spermatozoa, when it enters the bursa, does not go direct 

 to the intromittent organ, but ascends up the curved side of the 

 bursa, turns on itself, and passes through an arched, chitinous 

 canal, and then passes into the intromittent organ, so that when 

 conjugation takes place, which it does on the ventral side, the 

 male anchors itself by the hooked palpus of the second maxilla ; 

 then, bending its body down until the claws are close under the 

 vulva, in which position they take a firm hold of the female. 

 This act brings the double intromittent organ in close connection 

 with the double vagina of the female, and causes the emission of 

 the spermatozoa into the receptaculum of the female. The 

 length of the bursa from tip of chela to base is from the one- 

 hundred-and-sixtieth to the one-hundred-and-seventy-sixth of an 

 inch, its greatest width, the one-four-hundredth of an inch. By 



* The homologue of this is the vasa efierentia in the female. 



