xv, 6 Shaw: Camp bellosphaera 495 
that of other Volvocaceae. But this resemblance may be more 
apparent than real. 
DESCRIPTION OF THE TYPE SPECIMEN 
For the type specimen of Campbellosphaera obversa the one 
shown in Plate I, figs. 1 and 2, has been selected. Of twenty- 
three photographs of this species available at the time of writing 
this one best exhibits the characters of the genus and species. 
It is an asexual coenobium containing four embryos and three 
gonidia. The specimen was fixed with others from the same 
source in a chrom-acetic acid solution, washed, passed through 
gradually concentrated glycerin into alcohol, stained in succession 
with alcoholic Bismarck brown and alcoholic nigrosin, and 
mounted with a multitude of others in Venetian turpentine. 
The material was collected from a pond in Pasay, indicated 
in my notes by the letter J, September 22, 1915, fixed at 11.30 
in the morning on the following day, and stained and mounted 
during the ensuing season. The specimen was photographed 
with a magnification of 100 diameters on May 18, 1916 (the 
negative was accidentally destroyed after the making of two 
prints), and photographed again with a magnification of 200 
diameters on the 23d of the same month. The two photographs 
show the specimen in the same position but with different levels 
in focus. Three weeks later, June 15, 1916, the specimen was 
examined for the purpose of taking descriptive notes and found 
to be flattened into a discoid form and turned up on edge. Three 
years later, June 7, 1919, the specimen was found to be almost 
completely overturned from its position at the time of making 
the photographs. All it lacks of being completely overturned 
is that the posterior pole is about 45 microns higher than the 
anterior pole. The present aspect of the specimen is so nearly 
an exact reversal of the photographs as to arouse a suspicion 
that the photographs had been taken on reversed plates. The 
facts that the two photographs taken on different days agree, 
and that the specimen was seen on edge, makes it clear that the 
revolution really occurred. 
The coenobium appears to have been somewhat ovoid in form 
and measured at the time of photographing about 225 by 275 ^ . 
Three years later it measured about 200 ^ wide by 235 ^ long. 
The shrinkage thus shown to accompany the hardening of the 
Venetian turpentine seems to have been confined mostly to the 
cell membranes of the coenobium. 
The protoplasts of the vegetative or somatic cells are round 
