Lindstrom — On Zoanthmia Rugosa. 407 



function Iiad ceased. During growth tlie flat surface was elevated 

 above the body on which it originally rested, and became more 

 curved. It is probable that the shell became free when its size 

 became too large in proportion to its points of attachment, as in 

 Goniophyllum, or more clearly in Palcsocyclus porpifa. The form of 

 the shell is very variable. The conical shape is seldom, regular. 

 The apex is commonly bent towards the convex side. Sometimes 

 the shell is extremely long and narrow (Plate XIV. Eig. 10). In this 

 species, also, the animal reduced its shell and formed a new calyx 

 within the old one (Plate XIV. Fig. 12) ; this is not, however, to be 

 confounded with the budding as described below. 



The opening of the cbIjx (Plate XIV. Figs. 8 and 11) is semicircular; 

 it is highest at the flat surface. The interior cavity occupies almost 

 three-fourths of the total length in short and broad specimens, and is 

 only a shallow depression in the long shells. The bottom and the 

 walls of the calyx are covered with convex vesiculee, having a 

 diameter of nearly five millim. The bottom ends in a pit, which 

 continues on the concave wall. In the middle of the flat wall there 

 projects a short and bliint ridge or tooth, homologous with the median 

 iseptum of the other Bugosa. This wall is also covered with narrow, 

 close and indented strife, parallel to the middle tooth. They are very 

 short, and but few stretch over the vesicul^e before they terminate. 

 "When the shell is weathered it seems as if the flat wall were covered 

 with long and narrow rows of small depressed points, instead of 

 these septa of the second order, which are then very obscure. In 

 place of the middle tooth there is seen a shallow groove or depression. 

 The opposite vaulted wall is rather smooth above the vesiculse ; its 

 stries or septa are distant, low, and more indistinct. The middle one 

 opposite the tooth of the flat wall is more prominent and long, and 

 and reaches to the bottom of the pit. In the angles between both 

 the walls are seen small depressed points or holes, the openings of 

 root-channels. In the young shells (Plate XIV., Fig. 9), the mouth 

 of the calyx is more oblique, the primary septum is more prominent 

 than in the older, it almost reaches to the bottom ; the vesiculee and 

 the lateral septa are indistinct and small, the mouths of the root- 

 channels are very apparent. 



In the propagation of this species budding seems to have been of 

 great importance (see Plate XIV. Fig. 14). In thirty -two specimens 

 out of ninety young shells only six, from five to seven millims long, 

 are independently fixed. This attachment of the young to the parent 

 might, at first, seem quite accidental as when shells of other animals 

 (Syringapora, Cyathophylla, and Favositidce), hei\e grown in the interior 

 cavity of Calceola. In such cases, however, it is evident that the shell 

 had lain empty on the bottom, of the Upper Silurian sea for a long 

 time after the soft parts of the animal had been decomposed. The 

 operculum has only once been found attached to its shell, and the 

 shells themselves are generally covered with foreign bodies. All 

 idea of accidental attachment in the position of the young shell 

 ceases when it is seen that they are, 'without exception, fixed in the 

 angles between the flat and the vaulted wall, never on the walls, as 



