-SPONGES, &C. 
289 
Tunicates are represented in the Pliocene strata by a single species, 
probably LeptocUnum tenue, of which the spicules have been found at 
St. Erth by Messrs. Kendall and Bell. The only Pliocene hydrozoa are 
two species of ITydractinia,.H. ci/rcumvestiens, S. Wood, and H. pliocena, 
Alim. The former is very abundant in the Coralline Crag, usually grow¬ 
ing on TropJion alveolatus, but sometimes upon other gasteropods. Of 
sponges the only indications are the perforations made by GUona, and some 
spicules belonging to the Calcisponges noticed by Dr. Hinde as occurring 
abundantly at St. Erth. 
E 60798. 
T 
