iyo8] Rohertson. — Incrusting Bnjozoa. 265 



42. Membranipora spinifera (Johnston) Alder. 



PI. 15, fig. 15. 



Flustra spinifera Johnston, 1838, vol. 2, p. 266, pi. 9, fig. 6. 

 Flusira lineata, (part) Johnston, 1847, p. 349. 

 Membranipora spinifera, Alder, 1857, p. 247. 

 Membranipora cymh(eformis Hincks, 1877,, vol. 19, p. 99. 

 Membranipora spinifera, Hincks, 1880, p. 149, pi. 19, figs. 1, a, b, c. 



Zoaria forming large brown patches on rocks, pebbles, etc. 

 Zooecia elongated, oval, alternate (pi. 15, fig. 15) ; margin rather 

 wide, raised, calcareous, roughened with minute papillae ; with a 

 variable number of spines, 10, 12, or more ; two at the summit of 

 the zoopcium, very long and flaring outward and upward; a sec- 

 ond pair, very stout and directed outward; the remainder more 

 slender and bending inward, almost meeting over the aperture; 

 aperture occupying the Avhole of the front. Avicularium elon- 

 gated, articulated to the side of the zooecium about the middle, or 

 just above it; erect upon a pedicel almost as long as the second 

 pair of spines; mandible acute and directed outward. Ooecia 

 shallow, smooth, with a rib across the front. 



This species has been found at Orca, Prince Williams Sound, 

 Alaska ; found also in considerable abundance on the rocks and 

 seaweed at various points on the California coast. 



43. Membranipora tehuelcha (d'Orbigny)' Waters. 



PI. 15, figs. 16, 17; pi. 16, fig. 18. 



Flustra tchucJclia d'Orbigny, 1839-46, vol. 5, pt. 4, p. 17, pi. 8, 



figs. 10-14. 

 Bifiustra telmelcha d'Orbigny, 1850-52, p. 328. 

 Membranipora cuberculata Busk, 1859, p. 30, pi. 2, fig. 1. 

 Bifiustra denticulata, Sniitt, 1873, pt. 2, p. 18, figs. 89-91. 

 ? Amphihlustrum bituberculatum Ortmann, 1890, p. 29, pl.l, fig. 25. 

 Membranipora tehuelcha Waters, 1898, p. 674, pi. 48, figs. 6-8. 



Zoariuni incrusting stems and fronds of fucus with a white 

 calcareous incrustation covered with tubercles. Zooecia (pi. 16, 

 fig. 18), elongated, alternate; aperture occupying about two- 

 thirds of the front, depressed, surrounded by a calcareous border 

 on whose inner rim are four, five, or six short denticles or teeth. 

 Below the aperture, two thick, blunt, calcareous spines, sp., or 



