258 THE MICROSCOPE. 
And as for the Polyzoa themselves, our common gelatinous 
form (Pectinatella) is, in its season, the autumn especially, to be 
found studding the leaflets of aquatic plants with jelly-like 
globules from the size of a pea to those of a boy’s marble, and 
floating in submerged masses as large as the reader’s head in- 
cluding his hat. Such “finds” are the occurrence of every 
autumn day in the writer’s locality. 
These pinkish or reddish jelly-like masses are the aggregated 
homes of the Polyzoa discovered by Dr. Joseph Leidy, and by 
him named Pectinatella magnifica. The mass does not surround 
a single individual animal, but it is secreted and used as a domi- 
cile by an innumerable host of the little creatures, whose struct- 
ure is as interesting as their appearance is beautiful. It is from 
this colonial habit that the entire group of similar organisms 
has been named the Polyzoa, a Greek word meaning ‘many 
animals.’ Pectinatella is only a single genus of the order, while 
Pectinatella magnifica is the only known species of that genus, 
and one happily almost as common as the lilies that grow in 
the ponds with it. Pectinatella, however, is not the only genus 
that surrounds its colonies with jelly. There are two others, 
Cristatella and Lophopus, the latter not having been thus far found 
in this country. In England and in France, however, it occurs 
in some abundance, while Pectinatella has not yet been observed 
in either of those countries. 
Cristatella is usually a collection of animals arranged in from 
three to eight rows within an oblong or oval ribbon-like jelly 
mass, the entire colony varying in length from one to six inches. 
Ht is not to be found freely floating, or even just submerged, as 
Pectinatella often is, for it has the interesting ability to move 
slowly forward. It is only occasionally seen in the writer’s 
locality, for it is not very common here, and when observed it 
is usually clinging to the lower surface of water-soaked logs or 
sticks or twigs, or slowly travelling among the leaflets of aquatic 
plants. It is apparently not a believer in rapid transit, for one 
species can travel only a single inch in a day, while another form 
will in one day accomplish a journey whose extent will equal its 
own length. To know that it has moved, its position must be 
noted and again examined after an interval of several hours. 
Its movement cannot be perceived by the eye alone. The foot 
rule must be brought into use. ; 
