674 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Division 2. Articulata Busk, 1859 



(Camptostega Borg, 1926) 



The Crisias 



"Primary zoid erect, separated by a chitinous joint from the pro- 

 ancestrula; zoarium jointed; rhizoids present. Body wall a gymnocyst; 

 vestibular sphincter present; brood chamber a gonozoid, moderately 

 dilated in its middle part; polypide of gonozoid degenerating before 

 having been fullgrown," (Borg 1944:133). 



This division is clearly distinguished by the jointed zoarium, by the 

 presence of rhizoids, which are formed of jointed series of kenozoids, 

 and by the mode of development from the larva, all of which are differ- 

 ent from the other divisions. On attachment the larva forms a dome- 

 like structure, on the top of which the first functional zoid is produced 

 and from which it is separated by a chitinous joint. There is only one 

 family, the Crisiidae, with a number of genera, depending chiefly on 

 the structure of the internodes. 



The erect, jointed zoarial form is so strikingly different from any 

 other cyclostome type of growth that the members of this Division are 

 easily placed at once. 



Family Crisiidae Johnston, 1838 



The zoarium is erect and jointed, the zooecia in a single series or 

 alternating in two series, or without definite arrangement in the older 

 branches of Crisulipora; the internodes consist of one zooecium to many ; 

 attached by jointed radicles, rhizoids, which consist of a series of elon- 

 gated, tubular kenozooecia. The ovicell is an enlarged zooecium (gono- 

 zoid) more or less pyriform in shape, with the ooeciostome (pore) 

 terminal or nearly so. The characters of the ovicell and its ooeciostome 

 are essential for the positive determination of most of the species of 

 this family. 



Key TO THE Genera of Crisiidae 



1. Internodes of 1 or 2 zooecia; elongate filiform spines present . . 2 

 Internodes with 1 to many zooecia; no filiform spines .... 3 



2. Only one zooecium to an internode Crisidia 



Two zooecia to an internode, fertile internodes may have 3 



to 5 > the ovicell is free for much of its length and the 

 ooesciostome is on the dorsal side Bicrisia 



