The Evidence from Sexual Characters. 183 



The male has a capitulum, but no calcareous plates, 

 and its antennae, an., are not completely merged in the 

 peduncle. It also differs from the female in the pos- 

 session of an ocellus, or eye-spot It has mouth-parts 

 and limbs, and, except for the fact that all its parts are 

 somewhat rudimentary, it does not differ very greatly 

 from other barnacles, except as regards its reproductive 

 organs. 

 In other species of Scalpellum, however, as in Seal- 



Fig. 19. Female specimen of Ibla FIG. 20. Parasitic male of the samte 

 Cumingii. species. 



pellum Eegium, the male is still more rudimentary, and 

 has no mouth or digestive organs. 



In two other genera, Alcippe (Fig. 21) and Crypto"- 

 phyalus, the females, which are true females, with no 

 trace of male reproductive organs, differ very essen- 

 tially from ordinary barnacles, and they have fastened 

 to the outside of their bodies a number of very small 

 males. In the males of these two species, which are 

 shown greatly magnified at Fig. 22, there are a few faint 

 traces of muscular fibres, but the organs of digestion 



