PLATE 4 
EXPLANATION OF FIGURES 
24 Detail of a conglutinate of Lampsilis ligamentinus. The glochidia, still 
enclosed in the membranes, are less crowded together than those of fig. 28. and 
are embedded in a mucilaginous matrix. 
25 Glochidium of Lampsilis (Proptera) alatus. 
26 Three conglutinates of Obliquaria reflexa, removed from the marsupiuni 
X2. 
27 Two conglutinates of Lampsilis ligamentinus, removed from the mar- 
supium. One is shown from the fiat surface, the other on edge. X2. 
28 Detail of a conglutinate of Obliquaria reflexa, showing the membranes 
closely pressed and adhering together. 
29 Young mussels of Lampsilis ligamentinus, one week after liberation from 
the fish, showing various positions assumed in crawling, the ciliation of the foot, 
and the new growth of shell. 
30 Transverse section of two water-tubes of the gravid outer gill of Quad- 
rulaebena, showing the glandular epithelium on the interlammellar junctions and 
two embryos in an early cleavage stage. 
31 Transverse section of a single water tube of the marsupium of Lampsilis 
alatus, showing the much greater size of the tube than in the last figure, which is 
drawn under the same magnification. Several embryos in an early cleavage stage 
are seen in the tube. 
32 Highly magnified section of a portion of the glandular epithelium lining 
a water-tube of the marsupium of Quadrula ebena, showing the large mucus cells 
and several nuclei of leucocytes (1) with which the epithelium has become infil- 
trated. 
33 Section of young mussel, Unio complanatus, 11 days after attachment 
of glochidium to gill-filament, still in cyst which is beginning to break away. 
