NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 113 



Discoporella umbellata (Def ranee), 1823 

 Plate 11, figs 7, 8, 9 and 10 



The Cupularia U7nbellata of most older authors. 

 Cupularia canariensis, Robertson, 1908 :314. 

 Cupularia robertsoniae Canu and Bassler, 1923 :82. 

 Disco/porella umbellata, Hastings, 1930:718. 



The zoarium is usually shaped like a miniature umbrella, but is often 

 much deeper, bovvl-shaped, or even cup-shaped, or it may be a flat disc 

 and I have seen small colonies which were actually inverted when at- 

 tached on the inside of a shell. The latter habitat is rare as the larva 

 almost without exception is attached to a sand grain or other minute 

 object which it soon covers and extends beyond to become free, but still 

 carries its original attachment about with it at the center of the dorsal 

 side. The color varies from pale yellow in younger colonies to brown, the 

 color being in the ectocyst and especially in the avicularian mandibles. 



The zooecia are roughly rhombic in form and are spirally arranged ; 

 younger zooecia at the center of the colony are more elongate. The mural 

 rim is thin and smooth ; the descending cryptocyst heavy and granulated 

 and the horizontal lamina is formed from a number of spinous processes 

 which meet and fuse, leaving irregular opesiules on the sides ; these opesi- 

 ules are irregular in form and vary in number from 2 to 5, the usual 

 arrangement being 3 or 4 on each side with a median proximal one ; the 

 distal process forms the proximal border of the aperture. At the distal 

 end of every zooecium there is a vibraculoid avicularium, the brown man- 

 dible of which sometimes measures as much as 1 mm long. 



Distributed around the world in warmer waters. Common in the 

 West Indian region from the northern coast of South America to Beau- 

 fort, North Carolina. Recorded from the Pacific coast only by Robertson 

 {Cupularia canariensis) from San Pedro and Santa Catalina Island, 

 California, and by Hastings from Gorgona, Colombia, the Galapagos 

 Islands and Panama. Canu and Bassler recorded it from the Pleistocene 

 of Santa Monica, California, under the name Cupularia robertsoniae, 

 but I am unable to accept this as a new species after examining over a 

 thousand specimens from both the Pacific and Atlantic coasts. The elon- 

 gated zooecia of robertsoniae are duplicated on the young colonies of many 

 specimens of umbellata, the number of opesiules varies considerably and 

 the size of the zoarium is merely due to age. 



The range of distribution on the Pacific coast appears to be from 

 Point Conception, California, to Point Santa Elena, Ecuador, as none 

 were taken beyond these limits. Between these points the species is abun- 



