28 UNITED STATES NATIONAL MUSEUM BULLETIN 296 



I have seen this embedding of the male in Cryptophialus melampygos, 

 Lithoglyptes indicus (see fig. 5a), Trypetesa lateralis, and T. lampas 

 (see Berndt, 1903a, for a figure of the latter), and I have little doubt 

 that it is a general characteristic. 



I have tried ascorbic acid mixtures on males of Trypetesa lateralis 

 for an extended time, and this does not seem to be a stimulant for 

 either the development of a penis or for the discharge of sperm. 



Sexuality in the Cirripedia 



In the Crustacea, except for a few hermaphroditic forms (most 

 thoracican barnacles, a few notostracans, isopods, tanaids, penaeids, 

 cephalocarids, and probably Emerita), the dioecious condition is the 

 rule, although the condition is not as simple as implied by recent 

 authors. Green (1961, p. 68) does not recognize the many completely 

 dioecious barnacles, while Charniaux-Cotton (1960, p. 412) does not 

 recognize that self-fertihzation does occur in the common barnacles, 

 and perhaps does not occur in the parasitic barnacles. Smith (1960) 

 commented on the latter by pointing out that the unisexual condition 

 is not necessarily a reversion, but occurs in primitive forms. 



A wide spectrum of sexuality is found in the Cirripedia. One finds 

 pure hermaphrodites in some species, and hermaphrodites with dwarf 

 complemental males in others. In still others dioecious females are 

 inseminated by miniature males resembling females or cyprid larvae 

 in varying degrees of reduction. The details of the mechanism of 

 fertilization and the sexual cycle of some Rhizocephala have recently 

 been worked out by Yanagimachi (1961a, b), and Yanagimachi and 

 Fujimaki (1967). The sexual mechanisms, however, of the Acro- 

 thoracica and those Thoracica with separate sexes or complemental 

 males are not known. 



In the Rhizocephala the male is no more than a cyprid which lacks 

 the penis entirely. Yanagimachi (1961a, b) has shown that male and 

 female cyprids are morphologically distinct in the rhizocephalan 

 Peltogasterella socialis Kriiger. The male, as a cyprid, injects its 

 entire contents through the antennules into the female mantle cavity. 

 The male cells migrate into a special sac in the female and differentiate 

 into spermatozoa. 



In both the Thoracica and the Acrothoracica the species with 

 separate sexes show a reduction or loss of the penis (cf. Henry and 

 McLaughhn, 1965). 



Dwarf males, whose reproductive system is the only organ system 

 well developed, assure availability and close proximity to females. 



