Familia II. Surirelleae. 



Frustula solitaria, libera ( rarissime stipitata ) , plus rniuusve orbi- 

 cularia, ovata vel cuueata, nonnunquam flexuosa vel ephippiiformia, 

 rarius contorta. Yalvae planae, convexiusculae vel leniter concavae, 

 saepius carina leniter alata, costis plerumque validis radiatim dispositis, 

 aut centrum versus abbreviatis et tum aream circumdantibus aut ad 

 lineam mediam productis, nodulo centrali nullo. 



VIII. CailipylOfliscilS Ehrb. (1841): Frustula solitaria, 

 orbicularia, suborbicularia vel oblonga, curvata vel ephippiiformia, rarius 

 convoluta, costis validis radiantibus vel in nodulos solutis , e margine 

 latiusculo ortis. 



A. Frustula orbicularia vel suborbicularia. 



a. Area plus minusve dilatata et evidenter punctata 



(Calodiscus Malenh.). 



C. superbus (Calodiscus superbus Eabenh. Siissw. Diat. p. 12. 

 T. III.). Suborbicularis, vix curvatus ; margine latiusculo, inter costas 

 punctato-striato, area magna, orbiculari, subplana, obsolete punctata, in 

 vivo zonata. v. v. 



Diam. ad. }jn'" = 0,0053". 



Conf. Fig. nostr. 10. 



Hab. in paludosis submarinis terrae di Otranto Italiae australis. 



C. Horologium Williams. (in Ann. and Mag. of Nat. Hist. 1848. 

 Sm. Diat. I. p. 28. T. VI. F. 51. Pritch. p. 799.). C. magnus, orbi- 

 cularis, costis abbreviatis radiatim dispositis, intervallis punctatis ; area 

 maxima rotunda sublaevi. v. v. 



Diam. V20— V'12'" = 0,0045—0,0074". 



Hab. in limo maritimo et inter algas marinas maris mediterranei 

 et Adriatici haud infrequeUs nec non ad oras Angliae passim. 



