LYCASTIS QUADRATICEPS. 38 I 



Macellicephala violacea (Lev.). Incipient ; males and females 

 occur. Wiren, '07. 



Hesione sicula Delle Chiaje. With paired hermaphrodite organs. 



Bergmann, '02, 'o2 a . 

 Syllis corruscans Haswell. Anterior somites with eggs, posterior 



with spermatozoa. Haswell, '86 ; Benham, '96. 

 Ophriotrocha puerilis Korschelt. Protandric with hermaphrodite 



organs. Sexes distinguishable. Korschelt, '93 ; Braem, '93. 

 Nereis diversicolor Mueller. 

 Platynereis dumerili Aud. et Milne Edw. Both occasionally 



hermaphroditic. Caullery et Mesnil, '98. 



Lycastis qtiadraticeps Gay. 



t Caobangia billeti Giard. Egg-bearers only observed ; male 

 gonads not detected. Giard, '93. 



Sabella microphthalmia Verrill. Protogynous paired hermaphro- 

 dite organs. Gregory, '05. 



Amphiglena armandi Claparede. Ova in first ten abdominal 

 somites ; testes in last nineteen. Claparede, '64. 



Salmacina dysteri (Huxley). Fissiparous. Male gonads in from 

 three to five anterior abdominal somites ; ova in eighth to 

 twentieth. No relation between fissiparity and distribution of 



. gonads. Huxley, '55. 



S. cediftcatrix Claparede. Ova in anterior abdominal somites, 

 sperm cells in posterior ones. Claparede, '68. 



£. incrustans Claparede. Claparede, '68. 

 Piliolaria militaris Claparede. Claparede, '68. 

 Spirorbis pagenstecheri Quatrefages. Pagenstecher, '63. 

 6". borealis. Paired gonads. Ova in first two abdominal somites ; 

 male gonads in posterior ones. Schively, '97. 



5". Icevis Quatrefages. Ova in first two abdominal somites, sperm- 

 cells in all the rest. Claparede, '68. 



Among Polychaeta in which hermaphroditism has become estab- 

 lished we find two distinct conditions. These occur irrespective 

 of the systematic position of the species. In the one case male 

 and female gonads are present in the same somite. Sometimes, 



