90 THE ZOOLOGIST. 



echinoids (species not mentioned) in three of his eleve 

 examples. 



Polyzoa. — The remains of polyzoans, all of which were 

 Membranipora, were found by Eichelbaum in six cases. Living 

 colonies of Membranipora pilosa have been largely eaten by the 

 Sea-Urchins studied by me. The Membranipora may simply be 

 eaten along with seaweed which it encrusts, or it may be 

 scraped away from a hard substance. Several Mussels, whose 

 shells were nearly covered with Membranipora pilosa, have been 

 persistently scraped by the Sea-Urchins, and the polyzoans eaten. 

 Fronds of the Sea-Mat (Flustra foliacea) also have been devoured. 



" Worms." — Worms, including the bodies and tubes of poly- 

 chsetes, tubes of Pectinaria, and Spirorbs and Serpulids, were 

 found by Eichelbaum in eight cases. A Sea-Urchin has been 

 seen by me to perch itself on the top of a living Sting-Winkle, 

 and then to eat the empty tubes of Serpula which were attached 

 to the shell of the mollusc. Masses of Sabella penicillus have been 

 attacked, and portions of the tubes, and sometimes the worms, 

 eaten. Spirorbis is eaten in considerable quantity along with 

 the seaweeds to which it is attached. 



Ccelenterata, Porifera, and Protozoa. — Eeichelbaum found 

 remains of hydropolyps in eleven cases ; these were mainly of 

 Obelia, but also of Campanularia. Traces of sponges and sponge- 

 spicules he found in five Sea-Urchins, in two instances these being 

 the remains of Esperia. Protozoans, mostly rotalids, occurred in 

 eleven cases. The Sea-Urchins observed by me have eaten 

 living and dead masses of Obelia and Hydrallmannia falcata, 

 and small sponges attached to seaweeds. 



2. Vegetable Matter as Food. 



The remains of plants, which included diatoms and frag- 

 ments of algae, were found by Eichelbaum in each of his eleven 

 Sea-Urchins. Allen mentions a small Sea-Urchin, living in a 

 shallow dish of sea-water for several months, which devoured 

 large quantities of red seaweed.* Petersen, according to 

 Eichelbaum, f mentions remains of plants and diatoms found 

 in the Sea-Urchins. 



When the contents of the intestines of Sea-Urchins are 



* E. J. Allen, loc. cit., p. 474. \ Loc. cit., p. 225. 



