CRISIA. 281 



broadest patches I had ever seen ; there was much of the 

 shell covered with HippotJioa catenulata, much larger in 

 size than I had ever met with it before ; there was one spe- 

 cimen of Hippothoa divaricata ; one of Alecto granulata ; 

 several of Alecto major, and three or four of Alecto dilatans ; 

 one of what we thought was Pustulipora deflexa, and many 

 fine specimens of Diastopora obelia ; and as these were 

 located alongside of Alecto major and Alecto dilatans, they 

 were, at a single glance, seen to be so different, that I should 

 never have thought of comparing them. Alecto major and 

 Alecto dilatans may run into each other, but Diastopora 

 obelia, in its pretty, continuous, unbranched scurf, is evi- 

 dently, I humbly think, different from any of the three species 

 of Alecto. 



FAMILY CRISIAILE. 



Character. Polypidoms phytoidal, jointed, dichotomously 

 branched ; the cells tubular, disposed in one or two series, with 

 the circular apertures alternately looking to opposite sides. 

 Johnston. 



Genus VI. CRISIA, Lamouroux. 

 1. CRISIA EBURNEA, Ellis. (Plate XV. fig. 52.) 



