BUGULA CALATHUS. 83 



the South-Devon coast, on Eschara foliacea; off the 

 Thatcher rock, Torbay, in about 9 fins. (T. H.). 



The differences between the present species and B. fla- 

 bellata are almost entirely confined to habit and mode of 

 growth. The zoarium of the former is shaped like a shallow 

 cup, perfectly simple and without any trace of convolution ; 

 the shoots or branches which compose it are shorter, and 

 divided into a much smaller number of segments, than 

 those of the latter ; the growth is more spreading than 

 that of B. fiabellata, the shoots of which are stout, erect, 

 and much divided. The colour of the two, when dried, 

 presents a striking contrast. When living, B. calathus 

 is of a light straw-colour. If we examine the minute 

 structure, we find a close agreement in all essential points. 

 The cells, ovicells, and avicularia are all on a larger scale 

 than in the other species ; and the latter seem to ex- 

 hibit some slight differences in form and proportion of 

 parts. They are more elongate ; the head is more produced 

 behind, and not so much arched ; and the beak is perhaps 

 proportionally shorter, though there is a good deal of 

 variation in this respect. The striae are more clearly 

 defined; but they are present also on the avicularia of 

 B.flabellata. On the other hand, the shape of the cells 

 and ovicells, the number of the spines, the position and 

 general character of the avicularium are the same in both. 

 Both are multiserial; and in both the number of rows 

 ranges very much within the same limits. 



Mr. Norman describes the spines of the present species as 

 " stout and blunt ;" but when fully developed they closely 

 resemble those of B. flabellata. The upper are stouter 

 than the lower, but the latter usually (not universally) 

 taller than the former. They occupy the same relative 

 positions as in the other form, and exhibit the same differ- 



o2 



