258 University of California Publications. [ ZooLoGy 
lower in the colony develop on the front surface of the lower 
zocecia, below and to one side of the aperture. These rootlets 
invariably proceed straight downwards (Pl. VIII, fig. 34, r.). 
Often on a zocecium in the same internode, and on zocecia at 
higher levels, just above the lateral avicularia, other rootlets 
eurving upward, develop from a circular chamber slightly raised 
above the zocecial wall (wv. 7.).. These upward growing fibres are 
of much less frequent occurrence than in M. ternata and M. 
gracilis, and the chambers from which they proceed are of much 
simpler construction. On the upper half of the colony neither 
fibres nor chambers are found. 
In the habit of growth, greater compactness, greater develop- 
ment of spines, and scarcity of tendril-like fibres, this species 
resembles M. occidentalis rather than M. ternata. 
Menipea pribilofi is known only from the shores of Alaska, 
and the islands of Bering Sea, having been obtained in consid- 
erable quantity from St. Paul Island, Pribilof Islands; and in 
small quantity from Homer, Unalaska, and Yakutat, Alaska. 
Serupocellaria Van Beneden. 
Cellularia Pallas, 1766. 
Cellaria, Ell. and Sol., 1786. 
Scrupocellaria Van Beneden, 1844. 
Cellularia, Johnston, 1847. 
Canda, Busk, 1852. 
Scrupocellaria, Hincks, 1880. 
Zoarium jointed. Zowcia numerous in each internode, rhom- 
boid; aperture with or without scutum; a sessile aviculariwm at 
the upper, outer, lateral angle; a vibraculum at the lower outer 
angle, and generally a sessible avicularium on the front surface 
of each zocecium. 
KEY TO THE SPECIES OF SCRUPOCELLARIA. 
i. Vibracular chamber tonpey ery) Z0ccerimae serene See eee 2 
1. Vibracular chamber not on every z0@¢ium <2 2 3 
2. Vibraculum slightly longer than a zoccium  ...........-..--.--...-- S. varians 
2. Vibraculum as long\as three: zomeia ee S. diegensis 
3. Vibraculum not as long as a zocecium ..............2--.2-20------ S. californica 
