IOWA ACADEMY OP SCIENCE Vol. XXIV, 1917 
34 l 
da nt. Body length 13 microns, anterior flagellum 20 microns. 
(The species is separated from N. opocamptus Stokes by the 
relatively greater width of the dorsal concavity.) 
Subclass CHOANOFLAGELLATA. 
*Diplosiga species. 38, 39 and 40, figure 55. 
A minute, delicate, stalked form, having an elongate, parallel- 
sided loriea whose base is drawn into a point and whose distal 
end flares into a collar with a second less flaring collar within. 
Flagellum single ; body not filling the proximal end of the loriea. 
Nucleus central ; two posterior vacuoles. Stalk 34 microns ; 
loriea from base to top of outer collar 35 microns ; flagellum 30 
microns. 
At no time was the flagellum in this species seen to wave, 
although other signs of life were manifested in the vacuoles and 
in an amoeboid motion within the shell. In one specimen the 
protoplasm rose to the top of the loriea, was protruded in a 
shapeless mass and then retracted. . The dotted lines in the 
drawings indicate the probable limits of the concentric col- 
lars, which were however too delicate to be defined in any way. 
Professor Calkins after seeing the drawings has placed the 
form in the genus Impiosiga. The forms were found rather 
rarely in the goldfish tank which yielded the supply of Nuc- 
learia. 
Class II Phytomastigophora 
Subclass PHYTOFLAGELLATA. 
*Mallomonas fresenii S. K. 41 and 42, figure 56. 
Yellow-green chromatophores. Flagellum long, single. Shell 
oval,- of glassy imbricating circular 'plates bearing setose spines, 
or setas. Setas not more than thirty, immovable, curved. Mo- 
tion rapid. Shell without spines 25 microns. 
Only a few specimens of this rare form were found in water 
sent from Fairport, Iowa. The addition of dilute chlorotone 
to the water caused a sudden expulsion of protoplasm from the 
shell, which demonstrated that the spines belonged to the shell 
proper and not to its contents (see figure 42). Edmondson 
records finding a Mallomonas which he considers to be the species 
plosiii, although he was not able to make out the structure of 
its shell. 
