BY E. J. GODDARD. 473 



primitive position, in regard to the genus, in somites xi.-xii. 

 Castle has already considered the species from a phylogenetic 

 standpoint, and has placed G. heteroclita on the central stem. 

 From the above table it will be seen that G. stagnalis, G. fusca, 

 and G. elongata, in connection with the genital apertures, have 

 the male pore in the same position as that of G. heteroclita^ and 

 the female pore in the same position as that of G. comjjlanata, 

 G. concolor, G. parasitica, and G. elegans. Were the genital 

 apertures, under primitive conditions, united or separate ? If 

 separated, how many annuli lay between them ? 



Nothing in this connection, so far as I know, can be deduced on 

 recapitulatory lines from our knowledge of the development of 

 the genus, in regard to the positions of the genital pores. 



All members of the Hirudinea are hermaphroditic, and beyond 

 one or twoC?) species of Glossiphonia (G. heteroclita) and the genus 

 Seinilagenetay the sexual pores are separated by a number of 

 annuli, which number is frequently in accord with that of the 

 annuli composing a somite. In the Glossiphoniidce there is no 

 trace of a penis, as is found in many other leeches, and mutual 

 impregnation, as seen in other leeches, is very likely not possible 

 among the members of this group. This idea I draw from the 

 interesting fact noted by Whitman, that hypodermic impregna- 

 tion obtains in G. parasitica, and most likely in all species of the 

 genus; and, further, that no species (and many have been studied 

 attentively in freshwater aquaria, in various parts of the world) 

 has ever been seen to copulate, as do many other leeches. In 

 addition, the structure of the genital apparatus would seem to 

 strengthen this idea. 



From a study of the Hirudinea in general, it would seem 

 logical to conclude that the separation of the genital apertures is 

 really correlated with the possibilit}'^ of mutual impregnation. 

 An interesting fact can be noted, in that all members of the 

 genus from any part of the world — and most large regions have 

 some endemic species — fall into two groups, one of which has 

 the apertures separated by one annulus, the other being charac- 

 terised by the presence of two annuli between the pores. 



