■^^^^] Gcc: Behavior of Leeches 203 



Verrill (1872-1873) has presented an extensive systematic 

 account of our North American fresh-water leechas, but says 

 little in regard to general habits. In discussing the relation of 

 the Hirudinea to fisheries he writes the following: "The leeches 

 are related to the fisheries in three ways. Some of the large 

 blood-sucking species like Macrobdella decora and the species of 

 Hirudo attack many fishes directly, even when of considerable 

 size, and destroy them very quickly by sucking their blood ; and 

 the species of Icthyobdella and Cystohranchus are true parasites 

 of fishes, and, often when numerous, do them much injury. 

 Other kinds like the various species of Clepsine, Nephelis, Aulas- 

 tomum, etc., destroy all sorts of small mollusks and worms, which 

 otherwise might become the food of fishes. But, on the other 

 hand, certain kinds of leeches are fed upon to some extent by 

 the lake whitefi.sh and probably by other fishes." 



Apathy (1888) devotes considerable space to the description 

 of the locomotor movements of the various genera of leeches. 

 These are so distinctive in type in the various forms that he 

 feels warranted in the statement that "in der verschiedenen 

 Art und Weise der Locomotion sehe ich namlieh einen wichtigen 

 Fingerzeig fiir die Phylogenie. " 



Loeb (1894) in his work on the brain physiology of the 

 annelids discusses briefly the righting movements and general 

 reactions of decapitated leeches. 



Beddard (1896) brings together what is known in regard to 

 leeches generally. Particular consideration is given to classifi- 

 cation and morphology, relatively little attention being given to 

 the general reactions of leeches. 



Gibbs (1897-1899) in a very interesting note states that the 

 skate-leech Pontobdella muricata incubates its eggs. A female 

 of this species was secured mounting guard over a group of eggs 

 attached to the flat valve of a scallop shell, Pecten maximus. 

 The incubation period of this individual occupied at least 123 

 days. Of this behavior Gibbs says: "For what purpose the 

 skate-leech remains with its eggs during incubation appears 

 uncertain. One may presume that their protection is the chief 

 object; whether from active enemies or from the mere accumu- 

 lation of sand, etc., is doubtful." 



