270 University of California Publications. [Zoology 



It is the purpose of the present paper to describe the distri- 

 bution of the sense organs over the body of Microscolex elegans, 

 a California earthworm, and to make some comparisons with 

 Lumbricus agricola as described by .Miss Langdon. These two 

 worms are quite different as regards structure and habits \o 

 effort was made to work- out tlie connection of the sense organs 

 to the nervous system of Microscolex. 



MATERIAL AND METHODS. 



Microscolex is a small worm with apparently a limited distri- 

 bution. It has been found in Berkeley, but is far more abundant 

 in Golden Gate Park, San Francisco. Dr. Eisen ('94) has 

 reported it also from Mount Diablo and Sonoma County regions. 

 The worm is usually found in manure piles or amongst decaying 

 leaves. In Berkeley a pile of leaves was found which contained 

 no other forms than Microscolex il< units, while in the park in 

 San Francisco it was associated with Allolobophora I'm tida. II 

 was noted that Allobophora calignosa, a worm very common 

 throughout the State, was seldom found in the immediate 

 vicinity with these worms. 



Fresh material was used wherever possible, but after the 

 dry weather came preserved material had to be resorted 

 to. The worms were allowed to swim about a while in 

 water to free them from grit and dirt, and were then killed by 

 allowing' alcohol to drip into the dish at the rate of fit) drops 

 to the minute. In this way the worms were stupefied in from 

 two to three hours. From the drip they were transferred to 

 SO per cent, alcohol and held between glass rods to keep them 

 straight while hardening. When hardened they were preserved 

 in 9.5 per cent, alcohol. Material to be used in sectioning was 

 taken directly from the drip and killed in Flemming's solution 

 or corrosive sublimate and acetic acid. Sections 2 to 5 microns 

 in thickness were stained with Mayer's haemalum or Delafield's 

 haematoxylin. On the whole, material stained in toto with Dela- 

 field's hematoxylin gave the most satisfactory results. 



The cuticle was prepared in the following manner. Freshly 

 killed worms were split open along the mid-ventral line from 

 the mouth to the anus. They were then put into 30 per cent, 

 alcohol or water to macerate, when after two or three hours the 



