156 



BIOLOGY OF THE PROTOZOA 



many cases indicating their presence and dimensions. According 

 to Fran9e they are somewhat spirally rolled like a cornu'copia, the 

 free margin arising from the softer food receptive area a^d by its 

 movements directing food particles towarfl this area. In some 

 cases two such collars, one within the other, are present as in 



AC D 



Fig. 82. — Types of choanoflagellates. A, Codosiga jmlcherrimus; B, Diplosiga sccialis, 

 C, Salpingceca marinus; D, Collar type according to Frange. (After Calkins.) 



SalpingoBca entzii or S. marimis (Fig. 82). The second, outer, 

 collar here is regarded hy Dofiein as a periplastic rigid structure 

 which forms a part of the cup or house and is not morphologically 

 equivalent to the inner collar, which, like a pseudopodium, may be 

 shortened or lenthened, or drawn in and formed anew by the living 



