EXPLANATION OF PLATE XVIII. 



Figure 89. — Branchiobdella Kavenelii, (p. 624;) dorsal view, natural size. 

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

 91. — Pontobdella rapax, (p. 625 ;) dorsal view. 

 92. — Phascolosoma csementarium, (p. 627;) lateral view. 

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



94. — Pontonerua marinum, (p. 634;) female, lateral view, enlarged 15 diam- 

 eters ; o, eggs ; v, genital orifice. 



(Figure 94 was drawn from a living specimen, by A. E. Vcrrill ; all the others were drawn from pre 

 served specimens, by J. H. Emerton.) 



