NO. 1 OSBURN : EASTERN PACIFIC BRYOZOA CHEILOSTOMATA 35 



ELEGTRA Lamouroux, 1816 

 Genotype, Flustra verticillata Solander, 1786:15. 



Key to the Species of Electra 



1. No proximal spines, lateral ones long and numerous; the oper- 



culum bears a pair of long furcate, delicate chitinous spinous 



processes anomala 



Proximal spines present (but see crMj/M/Vn/a var.) 2 



2. A single median proximal spine 3 



More than one proximal spine 5 



3. A single proximal spine only ; operculum calcified, white. . . . 



crustulenta var. arctica 



Lateral spines also present 4 



4. Proximal spine regularly present, strong; 1 to 4 pairs of weaker 



lateral spines, the distal ones erect hastingsae 



Proximal spine weak or wanting, others slender and varying in 



number, often wanting ; operculum weakly calcified 



crustulenta var. 



5. A transverse row of several stout proximal spines; a strong 



branched scutiform spine on each side of the operculum. . biscuta 

 A long furcate spine on each side of the median proximal one, 



varying greatly bellula var. bicornis 



Electra crustulenta (Pallas), 1766 

 Plate 3, figs. 4 and 5 



Eschara crustulenta Pallas, 1766:39. 



Membranipora lacroixii, O'Donoghue, 1923:25 (? part). 



Electra crustulenta, Borg, 1931 :29. 



Membranipora crustulenta, Osburn, 1944:31. 



This species, which is common on both sides of the North Atlantic 

 appears not to have been recorded definitely from the Eastern Pacific. 

 The synonymy is so confused that it is not always possible to be certain 

 of the reference. The work of Borg (1931, "On some species of Mem- 

 branipora") has cleared up a great many points, especially concerning 

 the numerous variations. 



The zoarium is encrusting in a thin layer, often with narrow ramify- 

 ing branches of one to several rows of zooecia. The zooecia are rather 

 regular in distribution, elliptical in form, and separated by deep grooves. 

 The walls are moderately thick as a rule, finely granulated on the mural 

 rim and narrow cryptocyst. The smooth gymnocyst is often well de- 

 veloped, but under crowded growth conditions may be reduced to the 

 vanishing point. The mural spines vary exceedingly, from none to as 

 many as 6 on each side. The operculum is often more or less calcified 

 and shows white against the rest of the frontal membrane. 



