86 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



PLUTELLIN^. 



Plutellus 162 



Argilophilus 162 



Megascolides 162 



DIPLOCARDIN^. 



DiPLOCARDIA 168 



(Aleodrilus) 169 



(Omahania) , 169 



(DiPLOCARDIA) 169 



(Naillenia) 169 



Trigaster 201 



Zapotecia 205 



BENHAMIN^. 

 Benhamia 208 



DiCHOGASTER 221 



PERICH^TIN^. 



PONTODRILUS 241 



LIMNODRILID^. 

 Telmatodrilus 243 



Appendix 247 



Methods of Collecting 247 



Care of the Worms 247 



Narcotizing 247 



Fixatives and Imbedding 248 



Disappearance of Native Species 249 



Methods of Indicating the Thickened Septa 250 



Bibliography 251 



Index 254 



Explanation of Plates 256 



Introduction. 



These researches are based upon collections made in 

 various parts of North America during the last few years. 

 The paper. completes the account of all species of the Terri- 

 colide families mentioned, on hand at the time of going to 

 press. There remain to be worked up some new species of 

 Diplocardia from Nebraska, received from Professor H. B. 

 Ward, and some very interesting species of Benhamia and 

 Ocnerodrilus, collected by Mr. Robert E. Snodgrass on the 

 Galapagos Islands and on Clipperton Island. These speci- 

 mens were received too late to be described in the present 

 paper. 



