252 University of California Publications in Zoology. [Vol.6 



disk from which there grow tubular zocecia curving in opposite 

 directions, and forming a fan-shaped expansion similar to any 

 young tubuliporidian colony. The two-layered condition results 

 from the ridges which occur at irregular intervals over the 

 unilaminar sheet, sometimes in a longitudinal, sometimes in a 

 transverse direction, and which growing upward form the erect, 

 bilaminar layers (fig. 38) the laminae becoming highly convo- 

 luted. Zooscia tubular, alternate, the older zocecia of a colony 

 sub-erect (fig. 36), the younger arising near the growing edge 

 (<//•. id.) and elevated but slightly, if at all, above the surface of 

 the zoarium. Ocecium (oe.) an inflation of the surface of the 

 colony and involving a number of zocecia. Oceeiostome? 

 Ocecioporef 



In adult colonies the ovieell is frequently found, but unfortu- 

 nately it has been impossible to distinguish its aperture. It 

 frequently occupies a space in the hollows formed by the folding 

 of the laminae, near the upper or growing edge. 



M. meandrina has been obtained at three stations on the coast of 

 Southern California; growing on the roots of kelp at Whites Point, also 

 dredged off shore at San Pedro in from 17 to 32 fathoms, and again off 

 Coronado Islands in depths ranging from 18 to 21 fathoms. 



Idmonea Lamouroux. 



Idmonea Lamouroux, 1821. 

 Idmonea, Smitt, 1865. 

 Idmonea, Busk, 1875. 

 Idmonea, Hineks, 1880. 

 Idmonea, Harmer, 1898. 



Zoarium ramose, erect; branching dichotomous or irregular, 

 free or anastomosing. Zooscia tubular, immersed for most of 

 their length, orifice frequently projecting ; disposed on one side 

 of the branch only, in parallel, transverse, or oblique rows on 

 each side of a median line. 



As Harmer ('98) has pointed out, considerable confusion 

 exists in regard to the generic differences between Tubulipora 

 and Idmonea, and in his critical discussion of the species of 

 Tubulipora that investigator removes at least one species of 

 Idmonea to the genus Tubulipora, viz., I. serpens. The chief 

 difference between the two genera, according to most writers, is 



