VAN NAME: COMPOUND ASCIDIANS. 399 
digestive tract, and hence, when once started, might be increased as 
the muscles contracted, but unless there was an initial tendency to 
twist in a given direction, the uniform direction of the twist which 
prevails in most species would remain to be explained. Possibly the 
structures lying beside the intestinal loop (the rejiroductive organs in 
some groups, the epicardial sac and sperm duct in others) ma\' cause 
a displacement in one direction to be easier than in the other. 
In some sj)ecimens the stomach wall, which is very thin and easily 
thrown into irregular folds by the contraction of the animal, is, as 
noted by Alder (1863) and Bjerkan (1908), raised into numerous but 
very small and shallow areolations which show no tendency to be 
arranged in rows, but are quite irregularly distributed. In other 
specimens, it is difficult to detect the areolation. To what extent this 
is due to individual variation rather than to imperfect preservation, 
the writer will not attempt to decide from the limited material at hand. 
All of the three specimens above described were obtained by fisher- 
men on the Banks of Newfoundland, and were probably brought up 
from the bottom by catching on the fish-hooks or becoming entangled 
in the lines. The two large colonies were collected by Captain 
George W. Scott, in July, 1S71, in 40 fathoms. Virgin Rock bearing 
N. E. by N. 30 miles distant. 
In northern European waters, this is a quite widely distributed and 
locally abundant species. Alder (1863) records it from "deep water 
in ^Nloray Firth." Hartmeyer (1903, 1906) records examples from 
the Banks of Newfoundland and from various points on the coast of 
Norway in depths to 40 fathoms; also one from Helgoland. He 
reports it as abundant and reaching a large size on the Dogger Bank 
and Great Fisher Bank in the North Sea. Bjerkan (1905, 1908) 
records other Norwegian and North Sea localities, in depths to 1(30 
meters, as well as east of the Faroe Islands, 110 meters, and off the 
southeast coast of Iceland, 75 meters. Redikorzew (1907) records it 
from the Murman coast region. 
Genus Aplidium Savigny, 1816. 
Colony sessile, generally cushion-like or forming a thick crust. 
Systems often unrecognizable (in preserved specimens at least). 
Zooids small, the post-abdomen usually short. Branchial orifice 
six-lobed; atrial orifice with a smooth or lobed border. An atrial 
