12 Dr. G. Lindstrom on the Affinities 



to the family Porttince of the Perforate Corals. Beaumontia, 

 in so far as it can be separated from Favosites, belongs also to 

 this group, and not to the Monticuliporida?. Lace.ripora^ 

 Eichw., again, is nothing more than a highly perforated Favo- 

 sites. Alveolites, as represented by M. -Ed wards (Hist. Nat. 

 des Cor. vol. iii. p. 263), is an assemblage of most hetero- 

 geneous fossils, some having ])erforate walls, septa, and tabular, 

 and others totally void of these parts, their only common 

 character being the non-essential one of having the mouths of 

 the tubes oblique and semilunate. This character, however, 

 is far from being always present. Two very common Upper- 

 Silurian species, viz. A. Fougti, E. & H., and A. Lahechei^ 

 E. & H., show themselves to be genuine Favosites, being 

 primitively provided with erect polygonal corallites, the tubes 

 ultimately becoming reclined, with oblique mouths, as the 

 corallum grows out in a lamellar form, but the perforated 

 walls and the septa being still retained. Of the other species 

 there are some which, as the Devonian A. suborhicularis and 

 its allies, are rather referable to Coenites. A. repens and 

 A. seriatopor aides are finely branched forms, without septa 

 and with few tabulae, and cannot with any certainty be num- 

 bered amongst the corals as long as their initial stages are 

 imknown. Miclielinia, again, deviates from the Favositidge 

 through its more fully developed septa, its cystiphylloid dis- 

 sepiments (tabular), and the root-like prolongations given off 

 from the border of the corallites. The perforations in the 

 walls are homologous with the inner openings of these rootlets, 

 and not with the mural pores of the Perforata *. There are 

 so many points of affinity between Michelinia and the Cysti- 

 phylla, that the genus must be included in the same family 

 as the latter. Chonostegites, E. & H., resembles an ei'oded 

 Michelinia. 



We next have a clearly circumscribed family formed by 

 some genera which are characterized by having twelve septa, 

 all of the same size, and a peculiar coenenchyma composed of 

 small tabulate tubes. This family consists of Heliolites, 

 LyelUa, Plasmopora, Calapoeciaj and probably Thecostegites. 

 When a longitudinal section of a, Heliolites is comparedwith that 



et forma et septi3 Favositarum. Epitheca tenuis, lonoitudinaliter rugosa. 

 Superficies calycigera lata, plana. Calyces insequales, saepe in radios 

 crescentes, obovati, angusti vel circulares, polygonii et curvi. Muri in- 

 completi, perforati. Noduli corpore rotundo, processibus tenuibus inter 

 se conjuncti. Partes iufeiiores vel primarise polyparii materia calcarea 

 consolidatje. Superficies calycigera processus radiciformes emittit. 

 Species unica N. acuminata n. in Dalhem, Gotlandia, reperta. 



* Favositea inaxiuiiis, Troost, is a MicheUnia, and is perhaps the same 

 as the M. convcxa of Yandell and Shuuiard. 



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