122 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Tricellaria occidentalis (Trask), 1857 

 Plate 13, figs. 6 and 7 



Menipea occidentalis Trask, 1857 :1 13. 



Menipea compacta form triplex, Hincks, 1882:461 ; 1884:208. 



Menipea occidentalisj Robertson, 1905 :254. 



Menipea occidentalis, O'Donoghue, 1923 :17. 



Tricellaria occidentalis, Silen, 1941 :79. 



Zoarium bushy, usually not more than 25 mm in height ; the branch- 

 ing unusually regular; internodes of 3 zooecia, though 5 or 7 may occa- 

 sionally be present. The zooecia have about the same size and character 

 as in T. ternata, the opesia usually a little less than half as long as the 

 front. The scutum is diagnostic in position, as its base is attached much 

 below the middle of the opesia; it varies greatly in form from a mere 

 spine or simple fork (typical form) to a broadly branched structure with 

 as many as 8 points (var. catalinensis) . There are usually 3 outer and 

 3 inner spines. 



Lateral avicularia large, the triangular mandible and the rostrum 

 both hooked at the tip ; frontal avicularia wanting. 



The ooecia are globular and prominent, with a number of small pores. 



Trask listed the species from Cape Flattery, Washington, to Santa 

 Barbara, California. Robertson records it as far south as San Diego, 

 California, and Hincks and O'Donoghue from British Columbia. 



Hancock Station 287-34, South Bay, Cedros Island, Lower Cali- 

 fornia, 10 to 15 fms, is the most southerly station. It occurs abundantly 

 along the shores and around the islands of southern California and north- 

 ward to British Columbia. 



Tricellaria occidentalis catalinensis (Robertson), 1905 

 Plate 13, figs. 8 and 9 



Menipea occidentalis catalinensis Robertson, 1905 :255. 



This appears to be merely a nominal variety, as suggested by Silen 

 (1941:80). Every character mentioned by Robertson appears to inter- 

 grade; the number of zooecia in an internode is not constant, the form 

 of the scutum ranges all the way from a curved spine to as many as 8 

 points and the forked spines are not constant. 



O'Donoghue found that northern specimens of occidentalis varied 

 toward catalinensis. Okada (1929:15) found the same variation in Japa- 

 nese specimens. 



