2 16 hitroducHo7i to Animal Morphology. 



and Amphiglena, with many otoliths (in Fabricia and 

 Amphicorina with one). 



The capacity of repairing injury is very great. 

 Reproduction may occur asexually by gemmation 

 from the penultimate segment, as in Nais, Chaetogaster, 

 Eolosoma, Myrianida, &c. In the last, Milne Edwards 

 saw a chain of six continuous, the first with ten, the 

 second with fourteen, the third with sixteen, the fourth 

 with eighteen, the fifth with twenty-three, the sixth 

 with thirty joints. Of another species. Clans saw 

 1 2-1 6 new, four-jointed individuals in a chain. De- 

 tachment of some metameres, followed by the growth 

 of a head, is a form of fission occurring in some species. 

 Some species have asexual as well as sexual forms ; 

 the former give origin to the latter by budding. They 

 are dioecious, except Lumbricus,Protula, Amphiglene, 

 Spirorbis, and some Serpulse, and often dimorphic. 

 In Lumbricus the sex-organs are in a limited number 

 (mostly 8-15) of zonites, the glandular layers of the 

 integument of which are swollen dorsally and laterally, 

 forming a saddle-like eminence (clitellum), which is 

 separated from the lower unthickened part by a 

 muscular ridge on each side. The ventral setae of 

 this region are clasping for copulation. Each has a 

 single bristle. There are two pairs of testes, con- 

 nected to which are wide saccular vesicles into which 

 the semen passes. In each of these vesicles is a pair 

 of funnel-like organs, ending in a vas deferens, which 

 on each side unites with its neighbouring vessel, and 

 passing backwards, opens at each side in the base of 

 a bristle-like copulatory organ on the fifteenth ring. 

 The orifices have glandular lips. The spermatozoa 

 are short thin threads with swollen heads. The pair 



