300 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



age formula 45, IT, 9; rostral fin 

 small; oral cirri small; 31 pairs 

 of gonads ; oral sphincter over 

 4th myotome; ventral fin with 

 fin rays. 

 B. capense— Length 39-48 mm.; 

 myot. 75: formula 47, 19, 9; 36 

 oral cirri; no eyespot (?); 30 

 gonads ; rostral fin and oral cirri 

 normal. 

 (ii.) Species with a well developed pre-oral 

 lobe, into which the notochord is pro- 

 longed, 

 (a) Myotomes 71-73- 



B. indicum — Length 25 mm.; 

 myot. 71-73 ; formula 42, 14, 15 ; 

 pre-oral lobe 2 mm. long on an 

 average. Other characters as in 

 B. lanceolatum. 

 (B) Species in /cinch oral cirri are apparently 

 absent. 



B. pelagicum — Length 10-21 mm. ; 

 myot. 65-67; formula. 36, 16, 15; 

 26 pairs of gonads; ventral fin 

 with no fin rays ; eyespot very 

 prominent. 

 B. elongatum — -Length 60 mm. ; 

 myot. 79 ; formula 49, 18, 12. 

 Genus II. Asymmetron — Left metapleuron stops just 

 behind the anus, the right is continuous 

 with the median ventral tin; gonads 

 disposed in a single right series; oral 

 cirri with or without sense papilla 1 ; 

 inlra-bnccal tentacles 10-16; ventral fin 



