234 Henry Lustre OSBORN, 
rise to side branches on the ends of which the flame cells were 
strongly suspected, though not actually recognized. The system 
seemed to be in complete working order. 
The nerve commissure dorsal to the pharynx and the lateral 
nerve trunks were seen in the transverse sections, but they are 
smaller and less differentiated than in the adult. The animal 
however showed evidence by its many movements of having some 
coordinating apparatus. Sense organs were not recognized. 
The reproductive organs had not developed. A cluster of un- 
differentiated nuclei beneath the intestine (Fig. 80) as they are 
located in the place of the future gonads are probably their anlagen. 
An similar mass near the site of the future generative opening may 
be the anlage of the future terminal organs of the system. There 
is no indication of ovary, spermary or vitellaria as yet. 
Of the interval between the earlier phases of the segmentation 
of the egg and this young larva nothing whatever is known. We 
do not know where that interval is passed, or how long it is. If we 
dared to infer from the cases of Aspidogaster and Cotylogaster we 
should think that it could not be a very long time, this however 
would not be a justifiable conclusion. If they are to be accepted 
as a criterion and we are at liberty to suppose that the interval 
is short and passed by the eggs in a free state, they ought to be 
easy of development artificially, where as they do not develop arti- 
ficially, so that it seems perhaps to be indicated that a secondary 
host is needed to furnish the conditions. 
o) Summary. 
1. C. is confined [in Lake Chautauqua, but not in the United 
States generally| to Anodonta. 
2. The ventral sucker has considerable resemblance to that of 
Platyaspis lenoiri, but has 29 acetabula intsead of 25, this difference 
is however lessened by the existence of intermediate forms as 
variant forms in Lake Chautauqua, one of which differs from the 
condition figured by Porrier in having only one more acetabulum. 
3. The excretory system described for the first time, is unlike 
that of any other known member of the family. It has a single 
terminal dorsal pore, two independent rhythmically pulsatile bladders, 
a collecting vessel running directly to the level of the pharynx, a 
recurrent vessel, ciliated, directly continuous with the collecting 
