Lindstrom— On Zoantharia Bugosa. 409 



exterior ones, so that a very broad cardinal margin, composed 

 of the accumulated strata, projects in an oblique direction above the 

 interior surface. Galceola Gotlandica, ranked by T. Eoemer among 

 the BracMopoda, is thus found to coincide with the Bugosa, in 

 the form of its calyx, in the internal structure of the sheU, the root- 

 lets, and its external sculpture. 



Of all known forms it seems to me that G. Gotlandica most 

 nearly resembles Galceola Tennesseensis, F. Eoemer.^ It is true that 

 the rootlets are wanting, but a glance at fig. Ic. in Professor 

 Eoemer's work, makes it at once evident that the two species have a 

 great affinity. The base of both is covered with vesicul^, as 

 in Goniophyllum and CystipJiyllum : the same groove is seen in both 

 on the same side. Instead of the projecting tooth in the middle of 

 the flat wall, there is an elliptical depression, and the cardinal 

 margin is finely crenulated without strite. But these difi"erences are 

 no doubt produced in the same manner as in Galceola Gotlandica, 

 namely, by weathering, so that the tooth, or primary septum, 

 resembles that part in weathered specimens of Goniopliylhim and C. 

 Gotlandica. The sheU, to judge by figs. 1 h, e, op. cit., appears to 

 be quite as. irregular in its shape as C. Gotlandica. Fig. 1 a shows 

 in the centre of the so-called " area," the same riclge as the Goth- 

 landic species, only somewhat larger. The operculum (fig. 1 d, ep. 

 cit.) resembles more that of C. sandalina, with its triangular area, 

 -with the nucleus close to the cardinal margin. 



If we now extend our comparisons to the third known species of 

 the genus Galceola, the G, sandalina, we find true homologies 

 between it and the two preceding forms. We then only see acci- 

 dental exterior resemblances with the BracMopoda, amongst which 

 this, as well as the last two mentioned species, have so long been 

 numbered. The regular form of its shell, the similarity of the flat 

 surface with the area of the BracMopoda, and that of the middle 

 ridge thereon with a pseudo-deltidium, may explain its having been 

 retained in that class. Some authors have compared it to Gyrtina and 

 .Cyrtia; others again, in consequence of the "area" of the small 

 valve, with certain Stroplwmenidce.'^ But this " area " does not form 

 a strictly circumscribed part, nor does it possess peculiar sculpture, 

 characteristic of the species, and different fram that - on the rest of 

 shell, as in the Bvacliiopoda. On the contrary, this sculpture is quite 

 of the same nature, as on the rest of the surface, the lines of growth 

 continue without interruption on it. The area of the shell is longi- 

 tudinally- scrdptured by fine striae or folds, the centre ones forming 

 the ridge, which is considered by many authors to be homologous 

 with the pseudo-deltidium of the BracMopoda. But this ridge is 

 precisely the same as that met with in almost all specimens of 

 .'Zoantharia rugosa. Besides Goniopliyllum and CaZceo^a, there are a 

 great many Bugosa which have a flat surface, somewhat resembling 

 .an area, and almost all have such a one during their young state, 



1 Die Silurische Fauna des Westlichen Tennessee, p. 73, PI. v. figs. 1 a-e. 

 ^ Eine kleine grobfaltige Abanderuug (of Spirifer trapezoidalis) nannte Defrance 

 •€alceol(iheter€clyta." Quenstedt. Handbuch der Petrefactenkunde, p. 479. 



