6 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



base, or movable jaw-piece of the antennas just behind 

 the mouth can be clearly seen. Inside the antennules 

 can be seen the developing prehensile antennules of the 

 Cypris-stage, the newly-forming shell of which (Cypr. sh.) 

 can be seen retracted from the carapace. The first pair 

 of maxillae can be likewise seen retracted some distance 

 forward from the external processes in which they were 

 formed. 

 Fig. 23. Developing compound eye of a somewhat younger Nauplius 

 of the same species, showing the polygonal retinulae, 

 with their red pigment (which at the stage shown in 

 Fig. 22, has become black). 

 Fig. 24. Side view of the Cypris-stage of the same species just after 

 the moult, showing certain transitional features — 

 a\ prehensile antennule ; a 2 , relic of antenna ; cp. edge, 

 edge of carapace (not yet closed) ; /. /. frontal filament ; 

 fr. I. ap. aperture of fronto-lateral gland, marking former 

 position of horn ; Ibr. labrum ; mn. mandible ; mx 1 . first 

 maxilla ; mx-. second maxilla ; o. gl. oil globules ; rnf gl. 

 reniform gland ; th. thorax ; th. ret. retractor muscle 

 of thorax-abdomen. 

 Fig. 25. Ventral view of similar stage. Letters as in Fig. 24, also 



th. app 1 . first pair of thoracic appendages. 

 Fig. 26. Cypris-stage of an undetermined Cirripede, possibly that of 

 Chthamalus stellatus, obtained from Plymouth. 

 Lettering : — add. so. adductor muscle ; a 1 , prehensile anten- 

 nule ; hue. m. buccal mass ; ca. app. caudal appendage ; fr. I. ap. 

 aperture of fronto-lateral gland; int. intestine ; Npl. eye, Nauplius- 

 eye ; o. gl. oil globules (large and colourless) ; o. gl 1 . masses of minute 

 greenish yellow oil globules ; or. s. oval sac ; rnf. gl. reniform gland ; 

 st. stomach : th. thorax ; th. gg. cli. thoracic ganglionic chain. 



Fig. 27. Side view of Cypris-stage of Balanus balanoides. Letters 



as in Fig. 2G. 

 Fig. 28. Ventral view of same : the thorax lay obliquely in this 



specimen, an unusual condition. Letters as in Figs. 



26 and 24. 

 Fig. 29. Cypris-stage of same species after fixation. The antennae, 



by means of which fixation occurred, have been torn 



away, having remained attached to the rock. 



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