JAPANESE LAND LEECHES. 3Q2 



Orohdella agrees with Lu))i!)ncubdella in the number of the in- 

 testinal blind-sacs, and in that of the testicular capsules, differing from 

 it, however, in the presence of the acetabulum. As some of the larger 

 specimens of Orohdella have also a very diminutive acetabulum, the 

 difference mentioned should not be regarded as being of such weight 

 as to interfere seriously with tlie affinity of theae two genera. Thus, 

 Orohdella finds its nearest ally among the known leeches in Lum- 

 hricohdella. 



Systematic Position. 



The division of Hiriidinea into two families, GnatJiohdellidœ and 

 Elujncliohdellidœ is very natural and already universally adopted, but 

 the diagnostic characters for them have generally been based exclusive- 

 ly upon their well-known European representatives. Thus, for in- 

 stance. Apathy (1886) gives the following three ])oints as the distinctive 

 marks for ihiatliohdellidœ : "1. Der Oesophagus hat einen geraden 

 Verlauf, ohne vorstreckbaren Saugstecher. 2. Das typische Mittel- 

 körpersomit besteht aus 5 Ringen. 3. Die äusseren Nephridialaper- 

 turen befinden sich an dem Hintersaume des 5. Rinsres, und zwar, mit 

 Ausnahme von Hœmadipsa an der Bauchfläche." In order to receive 

 Orohdella^ which can belong to no other family, two out of these three 

 points must be erased. It is the first (jne only, that holds good for 

 Orohdella, the second is wholly untenable, and the third has to be 

 corrected thus :— " The external apertures of the nephridium are found 

 at the posterior margin of the last ring." That they open on the 

 ventral surface lias no value whatever for diagnosis, for, so far as I 

 know, there is no leech that has nephridial openings on the dorsal 

 surface. Apathy divides Gnathohdellidœ further into two subfamilies ; 

 Nephelidœ and Hirudinidce. This is also very reasonable, but the charac- 

 ters he gives to Nephelidœ are too limited to admit any other forms 



