NO. 1 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 101 



distinct. Avicularia more or less asymmetrical, cryptocyst not divided, the 

 wing developed on one side of the mandibular rachis. 



The species under discussion, O. alula, does not quite conform to the 

 generic description, as the rachis is usually straight and there is occa- 

 sionally a vestigial wing opposite to the developed one. Otherwise it 

 agrees with the genotype, O. marioni Jullien, 1882. 



Onychocella alula Hastings, 1930 

 Plate 11, figs. 5 and 6 



Onychocella alula Hastings, 1930 :715. 



Zoarium encrusting yellow to brown in color. The zooecia are ir- 

 regularly hexagonal, distinct ; cryptocyst depressed and tuberculate, con- 

 tinued around the sides and in front of the aperture; proximal border 

 of the aperture nearly straight, the opesiules indistinct. The operculum 

 is well chitinized, brown, with a bordering sclerite except proximally, 

 and it is well separated from the cryptocyst; it is surrounded at a little 

 distance by a chitinous framework which extends proximally to contact 

 with the cryptocyst. The avicularian chambers are symmetrical and with- 

 out a raised rostrum; opesia single and variable in size and form; the 

 mandible thin and straight, strongly hooked at the tip, sharply marked 

 off from the triangular base and toothed on the under side nearly its 

 whole length; wing narrow, very delicate and extending nearly to the 

 tip, occasionally a trace of a wing on the opposite side. 



Measurements : zooecial length 0.45 to 0.50, width 0.35 to 0.40 mm ; 

 onychocellaria length 0.35 to 0.40 mm, width 0.20 mm ; length of mandi- 

 ble 0.40 to 0.50 mm. 



Dr. Hastings recorded the species from Gorgona, Colombia, and 

 Balboa, Canal Zone, 15 fms. 



Hancock Stations: 23-33, La Plata Island, Ecuador, 10 fms; 114, 

 Catalina Island, southern California, 41 fms. Also Panama, Galtsoff col- 

 lection, Sta. 23, covering several square inches on a pearl oyster shell. 



Genus FLORIDINA Jullien, 1881 

 The cryptocyst is nearly complete, extending around the aperture, 

 with a strong angular process on each side; the opesiules are large and 

 usually very evident, marked off by the angular processes and extending 

 laterally from the proximal end of the aperture. There is much variation 

 in the form of the opesia. The avicularian chambers (onychocellaria) are 

 straight, without a distal canal and rounded at the tip ; the mandible is 

 broadly and equally bimembranous. Genotype, Mollia antiqua Smitt, 

 1873. 



