SEX-CHARACTERS ILLUSTRATED 69 



of Bonellia, an interesting green worm with 

 a flask-shaped body an inch or two in length 

 and a flexible bifid proboscis much longer 

 (see Fig. 11). But this is the female, for 

 the male is only about a hundredth of her 

 size and lives as a parasite within the oviduct. 

 It is one of tftie most extraordinary cases in 

 the whole Animal Kingdom. The micro- 

 scopic male embryos after swimming freely 

 by means of cilia, attach themselves to the 

 proboscis of a female, pass down to the gullet, 

 and eventually to the oviduct. They have 

 not even a mouth, and are little more than 

 minute bags of sperms. 



There is very little sex-dimorphism among 

 Echinoderms, but a very curious case is 

 reported by Koehler, an authority on the 

 group, who states that the males of one of the 

 brittle-stars, Ophiacantha vivipara, have five 

 arms, while the females have always more 

 (six to eight). 



GENERAL IMPRESSIONS. Taking a retro- 

 spect, we notice that in most cases the 

 positive character is on the male side. He 

 has an extra something which the female 

 does not possess in a developed state, if at 

 all. It is important therefore to recall two 

 or three examples of the converse. The 

 females of the frog genus Nototrema have a 

 pocket on the back into which the male 

 pushes the eggs. So far as we know the 

 marsupium is never more than a rudiment in 

 male marsupials. In the red-necked phalarope 

 the female is the more decorative bird. 

 Drone bees have not the sting which the 

 queens and workers possess. 



