Sub-class — Cirripedia. Order — Thoracica. 



Family — Balanid^. 



Cirripedia sine pedunculo ; scuta et terga musculis depressoribus instrucla ; reliquce 

 testa valva inter se immobiliter conjunct (2. 



Cirripedia without a peduncle ; scuta and terga furnished with depressor muscles ; 

 other valves united immoveably together. 



This family, which includes all true Sessile Cirripedes, may be divided into two very 

 natural sub-families ; namely, the Balaninse and Chthamalinse ; but as not one member of 

 the latter has been found fossil in Great Britain, and indeed only one, the Pachylasma 

 cjiganteum, in any part of the world, viz., in the recent beds of Sicily, this sub-family of 

 the Chthamalinse may be here passed over in silence. 



Sub-Family — Balanin^e. 



Rostrum cum radiis, sed sine alls : valva testa laterales omnes, ex uno latere alis, ex 

 altero radiis instructs : parietes fere aut porosi, aut ad interiorem superficiem longitudi- 

 naliter costati. 



Shell with the rostrum having radii, but without alse ; lateral compartments all having 

 alee on one side and radii on the other side ; parietes generally either porose, or longi- 

 tudinally ribbed on their inner surfaces. 



Genus — Balanus, Auct. 



Conopea (pars generis). Say. Journal Nat. Sc. Philadelphia, vol. ii, Part 2, 1822. 

 Messula (do.) Leach. Zoological Journal, vol. ii, 1825. 

 Chirona (do.) J. E. Gray. Philosoph. Transacts., 1835, p. 37. 



Valva operculares inter se articulates, sub triangulares ; valva testa 6 ; basis calcarea aut 

 membranacea. 



