1910] Robertson: Cyclostomatous Bryozoa. 251 



ti> ;i point as do spines, they Batten and expand into two lateral 

 blunt processes (dor. pro.). Those on the lateral zooecia expand 

 more to one side than the ether Int. t.) so that they are plainly 

 visible on surface view. Very often considerable debris lies 

 between the lower surface of a colony and the substratum. The 

 dorsal processes slightly raise the colony, or that portion of it 

 which they underlie, supporting it on tiptoe, as it were. The 

 loose attachment of these colonies is apparent in the ease with 

 which they are removed. 



As "Waters ('87) remarks, the contraction of the apertures of 

 the zooecia which MacGillivray makes so prominent a character is 

 not -very apparent and might well be overlooked. However, it 

 often occurs especially in those zooecia which show other irregu- 

 larities of form. 



T. pulchra is obtained at several localities on the coast of Southern 

 California: on the shore kelp at San Diego and dredged al various localities 

 off shore in depths ranging from 11 to 32 fathoms. 



Mesenteripora Blainville. 



Mesenteripora Blainville 1834. 

 Diastopora Milne-Edwards, 1837. 

 Bidiastopora (part), d'Orbigny, 1S47. 

 Ditaxia (part), Hagenow, 1851. 

 Mesenteripora, Woo, I, 1S4.4. 

 Mesenteripora, Busk, 1849. 

 Mesenteripora, d'Orbigny, 1850-52. 

 Mesenteripora, Busk, 1S75 



Zoarium erect, bilaminate. Zocecia opening on both surfaces. 

 On i in an inflation of the surface. 



96. Mesenteripora meandrina (Wood) Busk. 



PI. 23, figs. 36, 37. 38. 



Diastopora meandrina Wood, 1844, vol. xiii. p. 14. 



Mesenteripora meandrina, Bosk, 1859, p. 109, pi. 17, fig. 2; pi. 18, fig. 



4; pi. 20. fig. 2. 

 Mesenteripora meandrina, Busk, 1875, p. 29. 



Zoarium bilaminate. forming a contorted, convoluted mass 

 loosely enveloping stems and roots, especially the holdfasts of 

 kelp; sometimes forming a tangled mass with the narrow fronds 

 of seaweed (pi. 23, fig. 37) ; beginning as a simple, primitive 



