NO. 1302. 



AMERICAN PARASITIC ARGULID^-WILSON. 695 



papilla on either side of this external opening, but some are without 

 it. The walls of the ovary are muscular, and in most species exhibit 

 peristaltic movements similar to those in the intestine. In some 

 species the dorsal surface is beset with dark brown pigment spots, 

 arrano-ed in somewhat regular longitudinal rows. The eggs are spher- 

 ical wlien first formed, and are each developed inside a small petioled 

 bag, so that the whole mass takes on the appearance of a bunch of 



grapes. n ^^ 11 



As they grow they become ellipsoidal, and are finally packed 

 too-ether so tightlv as to become angular. Between the egg and the 

 membrane of the bag in which it is contained is a clear, jelly like sub- 

 stance which forms a sort of shell around the egg. The semen recep- 

 tacles are dark-colored spherical capsules lying in the anterior portion 

 of the abdomen lobes near the cloaca (fig. 22). From each capsule a 

 duct (.s\ d.) runs forward and inward to a hollow conical papilla {s. p.) 

 situated nearer the midline on the ventral surface. This papilla is in 

 the anterior end of an elliptical shield composed of several chitin 

 plates which covers the ventral surface of the abdomen around the 

 papilla and holds it securely in place. Near the center of the duct is 

 a blind app.'ndage. The papilla are strongly curved over inward 

 toward the midline, and both they and the shield plates are capable of 



motion 



motion. 1^-4. 



The outer end of the semen duct leading from the capsules fits into 

 the papilla as into a sheath and can be withdrawn or extruded at will. 

 Its tip is contracted and hardened into a sharp chitinous spine, and 

 when extruded this spine projects from the tip of the papilla and 

 comes in contact with the egg as the latter issues from the oviduct. 

 When withdrawn the papilla is closed and the semen is confined to the 

 receptacle and the proximal part of the duct. 



Glaus calls attention to the thickness of the eggshell and the con- 

 sequent necessity of a micropyle through which the sperm may enter 

 the egg. But he states that careful examination does not reveal any 

 micropvle, and gives it as his opinion that the sharp chitin spine at 

 the tip of the duct just noticed pierces the egg shell and makes thus a 

 passage for the sperm. 



However this may be, it is certain that the egg as it issues from the 

 oviduct, and is grasped between the bases of the posterior legs and 

 carried back into place on the underlying surface, must come forcibly 

 in contact with this spine and receive from it a discliarge of sperm. 



The male sexual organs may be distinguished first as essential and 

 accessory. The essential organs include the testes, an unpaired sem- 

 inal receptacle, the ducts leading from the testes to the receptacle and 

 from the receptacle to the sexual opening, and a pair of blind capsules 

 connected with the latter ducts (fig. 23). The testes are situated in 

 the lobes of the alxlomen in a position corresponding to that of the 



