ANALYTICAL INDEX. 



305 



CHAPTER IV.— continued. 

 Colonies, 

 Perpetuation, 

 Clusters of ova external, 

 Development of the young, 

 Plate XVIII., figs. 1-10 explained, 



§ 2. Sertularia thuia, 

 Hydra, . 

 Vesicles numerous, 

 Planula from the vesicle, 

 Vegetation by descent, 

 Plate XIX., figs. 1-6, explained, . 



§ 3. Pedicellina nutans, 

 Observed by Ellis, 

 Organic throughout, 

 An ascidian zoophyte, 

 Hydra with 14 ciliated tentacula, 

 Distortions, 



Professor Van Beneden, 

 Habits of the Pedicellina, 

 Its position doubtful, 

 Plate XX. explained, 



§ 4. Tobtjlaria sultana, Vol. I. Plate XII. Figs. 12, 13, 

 Not a Tubularia, 

 Of extreme rarity in Scotland, 

 John Welch, a fine artist, 

 Hydra, ....-• 



§ 5. Avenella fusca, Vol. I. Plate XII., Fig. 11, 

 Hydra ascidian, with 18-20 tentacula, . 

 Resembles a grain of corn, 

 A parasite, ..•••• 



§ 6. Triticella flava on an Ascidia, Plate XXXVI., Fig. 1, 

 Multiplied delineations useful, 

 Quiescent living animals infested by zoophytes, 

 Mr Milne Edwards, . 

 Triticella hydra with 20 tentacula, 

 Cell variable, . 



2d 



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