ENCHYTR-iEID^ 3 



the species become still more scarce, and those of Mesenchy- 

 trcBtcs seem to disappear altogether. 



San Francisco, 

 March 31, 1^00. 



Note. — This paper was finished and forwarded to the editor 

 a month or so before the publication of the ' Oligochaeta ' by Dr. 

 W. Michaelsen. Being unable to use the admirable work of 

 Dr. Michaelsen in the preparation of my paper, I was obliged 

 to postpone until proof-reading some important and necessary 

 changes in the nomenclature of genera, species and organs. 

 These changes I have now made. Thus I have followed Dr. 

 Michaelsen in changing Pachydrihis to Lumbricillus^ and I 

 have also adopted such terms as * ampulla,' ' peptonephridia ' 

 and others in order to make the terminology more uniform. 

 Since Dr. Michaelsen's Oligochaeta was published a few minor 

 publications by other investigators have appeared, containing 

 descriptions of species of Enchy tree idee, especially from the 

 southern part of Europe and the Alps. These species I have 

 as a rule left without consideration, the time being too limited 

 to enable me to make further additions and comparisons. 



The typss of all or nearly all the species described in this 

 paper have been sectioned up and are now in the form of micro- *T ^ ^^^ 

 scopical slides in the collection of the California Academy of ■ ' 



Sciences at San Francisco, Calif. The types of the Vega Ex- 

 pedition will be forwarded to the Royal Academy of Sciences 

 in Stockholm. Cotypes of the species collected by the Har- 

 riman Expedition have been deposited with Prof. Trevor Kin- 

 caid in the University of Washington, at Seattle, and with 

 Prof. W. E. Ritter in the University of California, at Berkeley. 



GUSTAV ElSEN. 

 August 15, 1903. 



EXPLANATION OF TERMS. 

 The following terms used In this paper require some explanation In 

 order to be fully understood. 



Accessory glands. — All glands which open around the base of 

 the sperm-ducts, but which do not originate inside the penlal bulb. 

 The accessory glands do not stand In any direct connection with the 



