PEREZ FARFANTE: SPERMATOPHORES OF AMERICAN WHITE SHRIMPS 



Figure IS.-Penaeus (Litopenaeus) setiferus. Thelycum, $40 mm 

 cl, off Galveston, Tex. 



straight or slightly emarginate along its median 

 portion, and produced laterally in a pair of convex 

 projections armed with long setae. The concavity 

 of sternite XIII is most important in that it serves 

 to lodge the sperm masses protruding anterodor- 

 sally from attached spermatophores. 



Disposition of the Compound 

 Spermatophore on the Thelycum 



The compound spermatophore is anchored to the 

 female much as it in P. schmitti. Anteriorly, the 

 geminate body lies on the mesial portions of the 

 coxal plates of the third pereopods (immediately 

 posteroventral to the gonopores), with the sperm 

 masses projecting anterodorsally through the 

 ruptured bulges of the sacs, to lie in a gelatinous 

 envelope fitting into the concavity of sternite XIII. 

 The wings embrace the sperm masses and then 

 extend over the coxal plates, leaving a passageway 



between them and the body of the animal. The 

 wings are proximally attached to sternite XIII 

 Oust caudal to the thelycal lamella) by their 

 posterior lobes, which are in close proximity, and 

 distally afl^xed to the sternite, or partly to the 

 latter and partly to the articular membranes of the 

 third pereopods. Posterior to the wings, the lateral 

 portions of the ventral walls are turned strongly 

 mesially thus reducing somewhat the lumen of the 

 sacs (Figure ID). This action may be responsible in 

 part for the transfer of the sperm masses from the 

 sacs to the concavity of sternite XIII at the time of 

 mating. The geminate body is elevated above the 

 sternum so that between the wings and flanges it 

 sometimes does not touch the animal, nor even do 

 the accompanying paired blades, which become 

 almost perpendicular to the sternum. Caudally, the 

 geminate body reaches sternite XIV, where the 

 vertical shelf formed by mesial portions of the 

 flanges lies between the thelycal lobes, or farther 

 beyond on the first pleonic sternite. The firm 

 elongate flaps project ventromesially in cons- 

 picuous fashion on each side of the geminate body, 

 whereas anterolateral portions of the flanges are 

 horizontally applied to the dorsal plates, in turn 

 attached to sternite XIV. 



I have examined a few females carrying only 

 those parts of the compound spermatophore which 

 are firmly anchored to sternite XIII; the geminate 

 body and adjoining structures have been lost. In 

 all of them, parts remaining affixed to the 

 thelycum (Figure 19) are almost identical: paired 

 masses of sperm lie exposed in the concavity of 

 sternite XIII, where each is contained in an in- 

 durate gelatinous substance which, in turn, is 

 tightly embraced by the wings. It appears that in 

 this species, as in P. stylirostris, when the sper- 

 matophores are released from the terminal am- 

 pullae of the male, the masses of sperm and jelly 

 are transferred from the posterior parts of the 

 sacs to the anterodorsal bulges which break under 

 pressure allowing sperm, surrounded by jelly, to 

 reach the thelycal concavity of sternite XIII. This 

 gelatinous substance is directly applied to the 

 concavity, there forming an envelope containing 

 sperm. Eventually, the compound spermatophore 

 splits, the geminate body falls, or is torn away, and 

 the sperm is exposed. 



In the impregnated females mentioned above, 

 the compound spermatophore had split in the same 

 fashion, leaving the sperm masses exposed to the 

 surrounding water, suggesting that this rupture 

 might be the means by which spermatozoa are 



481 



