SYNOPSIS GENERUM. 607 



1. Genus — Balanus, Auctorum. (Darwin, ' Balanidae,' p. 177.) 



Valvae testae 6 ; basis calcarea aut membranacea ; valvae operculares 

 subtriangulares. 



2. Sub-genus — Acasta, Leach. (Darwin, ' Balanidae,' p. 302.) 



Valvae testes 6 ; parietes et basis non porosa ; basis calcarea, cyathi- 

 formis, non elongata. Spongiis, aut raro Isidis cortici, affixa. 



3. Genus — Tetraclita, Schumacher. (Darwin, * Balanidae,' p. 321.) 



Valvae testae 4 ; interdum inter se externe confluentes : parietes poris 

 perforati, multis plerumque seriebus ; basis plana, irregularis, calcarea 

 aut membranacea. 



4. Genus — Elminius, Leach. (Darwin, 'Balanidae,' p. 345.) 

 Valvae testae 4 ; parietes non porosi ; basis membranacea. 



5. Genus. — Pyrgoma, Leach. (Darwin, 'Balanidae,' p. 354.) 



Valvae testae in unara confluentes ; basis cyathiformis aut subcylin- 

 drica, coraliis affixa. 



6. Sub-genus — Creusia, Leach. (Darwin, ' Balanidae,' p. 375.) 

 Valvae testae 4, radiis instructae ; basis cyathiformis, coraliis affixa. 



7. Genus — Chelonobia, Leach. (Darwin, ' Balanidae,' p. 382.) 



Valvae testae admodum crassae, 6 ; sed ex iis, valva rostralis intus 

 e tribus valvis rndimentariis conjunctis constat; basis membranacea; 

 scuta angusta, tergis crista articulari cornea conjuncta. 



[Sectio f f.] 



Scutum et tergum (ubi ambo adsunt) non inter se articulata ; basis 

 membranacea ; parietes saepe profunde plicati, lamina exteriore, ad 

 basin versa, plerumque imperfecta; branchiarum unaquaeque eduobus 

 plicis constat. Testa vertebratis vivis affixa. 



8. Genus — Coronula, Lamarck. (Darwin, 'Balanidae,' p. 397.) 



Valvae testae 6, aequali latitudine ; parietes tenues, profunde plicati, 

 plicis cavitates infra solum apertas efficientibus ; valvae operculares 

 orificio testae multo minores. Cetaceis affixa. 



9. Genus — Platylepas, J. E. Gray. (Darwin, ' Balanidae,' p. 424.) 



Valvae testae 6 ; unaquaeque bilobata et intus producta, ita ut 6 

 medias costas longitudinales efficiant, quae basin membraniicean ex- 

 trorsiis convexam sustinent. 



10. Genus — Tubicinella, Lamarck. (Darwin, ' Balanidae,' p. 430.) 



Valvae testae 6, aequali latitudine ; testa subcylindrica, orificio latiore 

 quam basis, pluribus cristis transversis virgata. Cetaceis affixa. 



