86 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



muscular fibres joining intestine with hinder pocket of 

 stomach ; st. stomach with hinder pocket projecting below 

 intestine, the hind part of the stomach composed of high 

 striated deeply staining glandular cells ; ces. oesophagus 

 suspended by contractile fibres and projecting into 

 stomach ; Ibr. labrum projecting below mouth. 



Fig. 10. Hinder part of tail (thorax-abdomen) of Conchoderma 

 virgata soon after first moult, to show telescoping of this 

 part. 



Figs. 11 — 16. Ventral views of the six Nauplius-stages of Balanus 

 perforatus, drawn to scale, and showing some of the most 

 important differences. The appendages are omitted, 

 though their sockets are shown in Fig. 16. 



Fig. 11. Newly-hatched Nauplius (Stage I). 



Fig. 12. Stage II of same. 



Fig. 13. Stage III of same. 



Fig. 14. Stage IV of same. 



Fig. 15. Stage V of same, showing segmenting thorax. 



Fig. 16. Stage VI of same. The position of the mouth shows by 

 the transparency of the labrum (Ibr.) The first pair of 

 thoracic legs alone are shown in this figure, the remain- 

 ing ones being omitted for the sake of clearness. 



Fig. 17. Cypris-stage of Balanus perforatus, ventral view ; drawn 

 on same scale as Figs. 11 — 16. 



Fig. 18. Portion of shell of same greatly magnified. 



Fig. 19. Side view of Stage V of Nauplius of Balanus perforatus. 

 Behind the brain (br.) are seen the circum-cesophageal 

 nerve cords and the sub -oesophageal ganglion. The 

 stomach shows numerous oil drops imbedded in the wall 

 and is suspended like the oesophagus and intestine by 

 contractile fibres. 



Fig. 20. View of very young adult form of Balanus balanoides 



from above, showing valves of shell; s. scutum ; t. tergum. 



Lettering the same in all figures, viz : — a. anus ; a x . antennule ; 



a 2 , antenna ; a 1 , s. socket of antennule ; a 2 , s. socket of antenna ; 



a. d. m. dorsal muscles to appendages ; br. brain ; c. carapace ; c. e. 



compound eye ; c. o. c. circum-cesophageal connectives ; c. s. caudal 



spine ; /. /. frontal filament (olfactory) ; /. h. fronto-lateral horn ; 



i. intestine ; Ibr. labrum ; m. mouth ; mn. mandible ; mn. s. socket of 



mandible ; ma; 1 . 1st maxilla ; nix 2 . 2nd maxilla ; iVp. e. Nauplius-eye ; 



oe. oesophagus ; o. g. oil globules ; s. stomach ; s. g. sub-cesophageal 



ganglion ; t. tail (thorax-abdomen) ; th. thorax ; t. f. m. flexor muscle 



of tail ; t. I 1 , first thoracic leg ; t. t enlarged ectodermal cells of 



tail (ventral plate). 



