THE BURROWING BARNACLES (CIRRIPEDIA: ACROTHORACICA ) 25 



purple granules are scattered through the body of some species. 

 Yellow organs, representing perhaps stored food droplets or glands, 

 are often present. The integument is not pigmented, but may be 

 variously equipped with clear teeth on the end opposite the first 

 antennae, rectangular or polygonal plates often bearing a number of 

 spots appearing to be pegs or other rugose elevations (see fig. 43, 

 electron micrograph), and hairs, generally around the end opposite 

 the first antennae. 



The presence of a penis in some species has been a big question, 

 yet unresolved. Most species have a definite penis which can be 

 pulled out to many times the body length. That this is a feature 

 which matures late in the hfe of the transient and expendable male 

 is evident in K. Jloridana, where a routine examination of many males 

 by Wells and myself netted each of us only one specimen with a penis. 

 I studied fifteen mature males carefully before I found another one. 



Ultrastructure of the Male and It8 Sperm 



Gluteraldehyde-osmium treated males of Trypetesa lateralis were 

 sectioned, and examined with an electron microscope for details of 

 the structure of the male and its sperm. 



The gross structure of the male seems somewhat acellular. The cell 

 boundaries appear to have broken down and the developing spermato- 

 zoa appear to be dispersed in the central region of the organism. The 

 exterior cuticle appears to be laminar and composed of six or twelve 

 layers, depending upon interpretation. The surface of the cuticle 

 exhibits a grooved or pegged effect (fig. 43) . 



In the region of the developing spermatozoan, many transverse 

 and partial longitudinal sections could be observed in the electron 

 photomicrograph. The head region could not be definitely discerned. 

 The sperm axoneme (flagella or tail) appears to be composed of the 

 typical nine plus two arrangement of microtubules (fig. 44). There 

 appears to be two accessory structures. One is a dense body which 

 is probably analogous to the "outer fibers" of classical spermatozoa 

 structure. The other appears to be an accumulation of granular 

 material. Both do not appear to travel the entire length of the tail, 

 since transverse sections can be observed which show the dense body 

 only (fig. 44a), a granular region only (fig. 44c), and both the dense 

 and granular regions (fig. 44b). Thus there appears to be a region 

 where the two overlap. It was not possible to determine the anterior 

 end. Figure 44d shows a longitudinal section through the granular 

 region only, and figure 44e shows a longitudinal section through the 

 dense region and a small portion of the granular region at one end. 



