THE LEECHES OF THE U. S. NATIONAL MUSEUM. 



By J. Percy Moore, . 



Instructor in Zoology, Univo'sity of Pennsylvania. 



Through the courtesy of the curators the collection of leeches con- 

 tained in the U. S. National Museum has been placed in my hands for 

 study and determination. Though small, and much of it poorly pre- 

 served, the collection has proved an interesting one. None of the forms 

 had previously been identified; several have been found to be unde- 

 scribed, several others have been mentioned in the literature but once 

 or twice, and many are here recorded from new localities more or less 

 remote from those previously known. The material has been drawn 

 from various parts of the world, but it is to be regretted that our own 

 American leeches are so poorly represented. Our fauna is a rich one, 

 but is, perhaps, well known to but one person, who has as yet shared 

 but little of his knowledge with the scientific public. We are still in 

 nearly complete ignorance of the number and distribution of the species, 

 and many interesting morphological questions remain to be elucidated. 

 But one attempt has been made to systematize our knowledge — that of 

 Prof. A. E. Yerrill twenty-five years ago — and that upon very inade- 

 quate material from comparatively few localities. It is to be hoped 

 that a greater interest will be taken in making well-preserved collec- 

 tions, and that our National Museum will soon have gathered together 

 a complete series, not alone of leeches, but of annelids generally and 

 other worms as well. 



This is perhaps not the most suitable occasion to enter upon a dis- 

 cussion of any of the broader or more theoretical problems of morphol- 

 ogy upon which the collection throws light. There is, however, one 

 matter of especial interest to the systematic student to which some 

 reference may profitably be made. I refer to the annulation of the 

 somite. My observations on this subject accord perfectly with the 

 views exi)ressed by Whitman (5 and 6) and later by Lang (4) and 

 Blanchard for the Glossiphonidte, Hirudinidffi, and Herpobdellidse, and 

 I am pleased to be able to extend them to the Ichthyobdellidae also, 

 which has, I believe, not previously been done. Apathy (1), who has 

 made the most important recent contributions to the external morphol- 

 ogy of the latter family, takes a precisely opposite view to that of 



Proceedings U. S. National Museum, Vol. XXI— No. 1 160. 



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