30 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvii. 



12. SECONDARY SEXUAL CHARACTERS. 



In many cases the males and females are alike in general characters, 

 although there may lie slight differences in size and proportions. In 

 some instances, however, differences occur of the following nature: 

 the antennie in the males may be longer than in the females; this is 

 true of the Ligiidai for example. The males of Llgia haudiniana 

 Edwards also have a fringe of bristles or stiff* hairs along the carpus 

 and the merus of the first pair of legs, which character is entirely 

 wanting in the females. Ligia exotica Roux is provided with a proc- 

 ess extending from the propodus of the first pair of legs in the males, 

 this process being absent in the females. The males of Corallana 

 tricornis Hansen, Corallana quadricornis Hansen, and Corallana sex- 

 icornis Richardson have in the first species named three spines on 

 the dorsal surface of the head, in the second species four spines 

 on the head, and in the third species four spines on the head and 

 two on the basal joints of the antennulte, the head of the female in 

 all these species being entirely unarmed. 



Among the Tanaidse and the Apseudidse the first pair of legs of 

 the males are much more robust and ver}^ much larger than those of the 

 females, although they are usually similar in structure. The males of 

 several species of the genus Leptochelia Dana have greatly elongated 

 first gnathopods and antennge while the same appendages in the females 

 are greatly reduced. 



The genera of the Janiridse, in which the first pair of legs of the 

 males is different in structure from the other pairs, show a similarity 

 in structure in all seven pairs with the females. Carpias hermudeims 

 Richardson, which presents this tendency in the extreme, being 

 remarkable for the great size and peculiar structure of the first pair 

 of legs, exhibits no peculiarities of this kind in the female. The legs 

 of the first pair in the species, Stenetrimn stehbingi Richardson, differ 

 in form from those of the female, both, however, being chelate in 

 character. 



In the Sph^romidse the genus Cilica&a Leach has the first abdominal 

 segment in the male produced in a long spine or process, which, accord- 

 ing to Haswell, is sometimes wanting in the female. The males of the 

 genus Isodadus Miers have the seventh thoracic segment produced in 

 a long spine, which is not developed in the female. Cycloklura Steb- 

 bing, an Australian genus of the Spliffiromidge, has the seventh seg- 

 ment of the thorax produced into a large dorsal spine, at least in the 

 male. Ceratocejjhalus Woodward, also a Sphan'omid genus, has the 

 head of the male drawn out into three large processes, of which 

 the middle one is much the longest; in the female faintly marked 

 projections take the place of these processes. The sixth segment of 

 the thorax in Campecopea Leach is produced in a long tooth in the 

 male, but not in the female. 



