66 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
out exception, in the anterior portion of the small intestine only. Sec- 
tions through this part often reveal great numbers of cysts (Plate 6, 
Fig. 75). They belong to the Polycystidea. Figure 73 (Plate 6) shows 
a very characteristic appearance of a living specimen, and Figure 74 that 
of one filled with sporocysts. 
In sections (Fig. 76) the protomerite (primer.) is seen to be com- 
pactly filled with protoplasm, the anterior half of which staims more 
deeply than the rest. The posterior half appears to be made up of 
globules somewhat flattened by mutual pressure. In living specimens 
the anterior portion of the protomerite is quite transparent, being free of 
all coarse granules (Fig. 73). 
The deutomerite (Fig. 76, deu'mer.) is generally only loosely filled with 
a coarse protoplasmic network. It contains the large, round nucleus, gen- 
erally situated quite centrally. Within the nucleus is always to be found 
a single large deeply stainable nucleolus. 
In conclusion, I wish to express my very deep indebtedness to Dr. 
Mark for whatever there may be of value in this paper. The work was 
taken up at his suggestion, and carried on under his very kind and care- 
ful supervision. 
CAMBRIDGE, May 12, 1896. 
