458 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Mediterranean form as figured by Hastings (fig. 86) and by Barroso 

 (1919, text figs. 11 and 11a) is more pointed at the proximal border 

 and the attachments are less separated. 



Described by Busk from Mazatlan, Mexico, and recorded by 

 Hastings from Taboga Island, Panama; Gorgona, Colombia, and the 

 Galapagos Islands. In the Atlantic recorded as verruculatum from 

 Massachusetts to Brazil. 



Hancock Stations: taken at 34 stations ranging from the Galapagos 

 Islands to southern California; Port Utria, Colombia; Taboga and 

 Secas Islands, Panama; Playa Blanca, Costa Rica; Tenacatita Bay, 

 Mexico; Socorro Island, west of Mexico; Angel de la Guardia and 

 Isabel Islands and Agua Verde Bay, Gulf of California; San Benito 

 Islands, west of Lower California; and common along the shores and 

 about the islands off southern California, as far north as Point Con- 

 ception. Shore to 100 fms. 



Rhynchozoon tumulosum (Hincks), 1882 

 Plate 54, figs. 4-5 and 12 



Schizoporella tumulosa Hincks, 1882:252; 1884:19. 

 Schizoporella tumulosa, Robertson, 1908:293. 

 Schizoporella tumulosa, O'Donoghue, 1923 :37 ; 1926 :56. 



Zoarium encrusting shells and stones, older colonies sometimes 

 multilaminar and roughened. Zooecia (marginal) varying greatly in 

 size, 0.45 to 0.65 mm long by 0.25 to 0.40 mm wide, ovate and 

 arranged regularly in quincunx; distinct, the front inflated with 7 to 

 9 areolar pores on each side, and with costate ridges. The primary 

 aperture is slightly broader than long (0.13 to 0.15 mm wide by 

 0.11 to 0.13 mm long) with a shallow sinus proximally; vestibular 

 arch definitely beaded. The primary peristome is at first low and thin, 

 but soon becomes elevated except on the distal border. A large globose 

 suboral avicularian chamber is located at one side of the midline, its 

 rostrum overhanging the aperture and directed laterally; the long- 

 triangular avicularium and the rostrum both sharply hooked at the tip. 

 Only two or three marginal rows show these characters, after which 

 secondary calcification completely changes the appearance. The frontal 

 becomes very thick, costate, corrugated or tuberculate; frontal avicu- 

 laria make their appearance, some of them short-triangular, others some- 

 what longer and more acuminate; an umbo, low or high, thick or 

 pointed, usually rises above the base of the suboral avicularium ; the 

 side of the peristome rises with a notch (spiramen) between it and the 



