24 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY, 
and Stauractinella, are both deep-sea sponges, but are also found in 
shallow water. Figures 24, 25, 26, 30, and 31 are similar to deep-sea 
recent forms figured by Carter, while the Monactinellid sponges are 
shallow water forms. Dr. Hinde concludes that the sponges in the 
Horseford flint, *do not show conclusively the depth of the water of the 
deposition." ! 
In the Challenger Reports, Volame on Deep-Sea Deposits, Mr. Murray 
takes the position that the chalk was not the same as the present 
globigerina ooze, because the species of Foraminifera in the chalk are 
principally shallow water forms. However, the appearance of the 
nodules so seldom in the cretaceous formations seems to indicate a very 
peculiar combination of circumstances which existed but once in a great 
cycle of changes. From its proximity to known shore lines, we may 
judge that this formation was not in the deepest sea, yot from the forms 
of animal life preserved in it we may conclude that it was beyond the 
continental shelf, in water deep enough to secure the conditions necessary 
for long periods of time. 
! Fossil Sponge Spicules of the Upper Chalk, p. 76. 
