CRISIA. 281 
broadest patches I had ever seen; there was much of the 
shell covered with Hippothoa catenulata, much larger in 
size than I had ever met with it before; there was one spe- 
cimen of Hippothou 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 Drastopora | 
obelia, in its pretty, continuous, unbranched scurf, is evi- 
dently, I humbly think, different from any of the three species 
of Alecto. 
Famity CRISIADA. 
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, Lamouroue. 
1. Crisra EBURNEA, Ellis, (Plate XV. fig. 52.) 
