EXPLANATION OF PLATE XVIII. 



FIGURE 89. Branchiobdella Ravenelii, (p. (524 ;) dorsal view, natural size. 

 90. Malacobdella obesa, (p. 625;) dorsal view. 

 91. Pontolxlella rapax, (p. 625 ;) dorsal view. 

 92. Phascolosoma ccementarinm, (p. 627;) lateral view. 

 93. P. Gouldii, (p. 627 ;) lateral view, reduced one-half. 



94. Pontonema inarinum, (p. 634;) female, lateral view, enlarged 15 diam 

 eters; Oj eggs; v, genital orifice. 



(Figure 94 was drawn from a living specimen, by A. E. Verrill ; all f\e others were drawn from pre 

 served specimens, by J. H. Emerton.) 



I 





