Pontoscolex Schmarda. 



This genus of terrestrial oligochaeta is undoubtedly one which requires more 

 careful study and revision, hardly two investigators agreeing upon the characteristics 

 of the most common species, Pontoscolex corethrurus. Having had opportunity to 

 collect and study this genus on the Pacific coast of Mexico and Central America, I 

 have in preparation a larger paper on this subject, based on the investigation of spe- 

 cimens fixed and treated according to modern microscopical methods. In the present 

 paper I have no space for entering on the relative value of those species which stand 

 near Pontoscolex corethrurus, nor on the advisability of joining them under one single 

 name, as has been done by Beddard and Rosa. In the following I will, in order 

 not to mix things up more than they are, refer to the Pontoscolex corethrurus, which 

 I have investigated, as Pontoscolex corethrurus mexicanus, by which I will simply 

 indicate that the specimens come from Tepic in Mexico, and that they differ in some 

 respects from Pontoscolex corethrurus as described by Perrier, Rosa, Horst, Bed- 

 dard, etc., and from which mine may or may not be a distinct species or variety. 

 A detailed description will not be entered on, only a short definition, together 

 with some notes on the peculiar sense organs in the epidermis of this worm. This 

 paper will then consider as follows 



i. Table of Species of Pontoscolex. 



2. Pontoscolex Lilljeborgi n. sp. 



3. Pontoscolex corethrurus mexicanus, definition of species. 



4. The auditory sense cells of the last species. 



