1910] Robertson: Cyclostomatous Bryozoa. 241 



of a colony containing three or five zocecia ami rootlets ; the upper, 

 and terminal internodes, from eleven to nineteen zocecia, and 

 even twenty-two and twenty-eighl or more. Branching alternate, 

 the longer internodes possessing two branches. In internodes of 

 seven zocecia or fewer, branches arising on the third or fifth zoce- 

 cinni; in longer internodes, branches arising from the seventh 

 or ninth, hence branching begins high up in the internode. Basis 

 rami (pi. 19, tig. 13, ha. r.), long, tapering, not wedged in. Joints 

 light colored, yellow or amber. Zocecia extremely long and 

 slender, connate throughout their whole length; aperture cir- 

 cular, hyaline, slightly constricted and bent forward. Ocecium 

 (oe.) elongated, connate throughout its length, the fifth or 

 seventh member of the internode. Ocecial int( mode usually long, 

 giving rise to two branches, one below the ovicell. the other orig- 

 inating on the zooecium which pairs with it. Ocet iostomt (oest.) 

 at the summit of the ovicell; the dorsal wall of the oceeium 



extending upward and forward covering th iiostome as 



with a lid or cap, the operculum (fig. 14, op.)-. Oceciopore (ocp.) 

 a semicircular slit, opening vent rally. 



C. operculata differs from the other biserial Crisias of this 

 coast in the ocecial aperture as well as in the branching of the 

 ocecial internode. Although the quantity of material on which 

 this diagnosis is made is small, yet there were seven perfect, 

 ovicells all possessing the peculiar covering over the oeeeiostome 

 for which the species is named. Fig. 15, which represents the 

 front wall of the ovicell as broken away, shows clearly the 

 mode of formation of the operculum, and the manner in which 

 the oceciopore is formed. In all the other biserial Crisias de- 

 scribed in this paper, at least of the zocecia adnate to the 



dorsal surface of the ooecium gives rise to a branch. In this 

 species none of the zocecia adnate to the dorsal surface of the 

 ocecium produces a branch. 



C. operculata has been obtained with ovicells at one station on the 

 Southern California coast, depth not known; probably abundant without 

 ovicells. 



