82 CALiFOKNiA aoaukmv of sciences. 



cral dpscription of tlicni will he siiporfliions. The spur is directed l)ack\var(ls and the 

 two tolds are directed upwards in al)Oiit right angle to the spur and narrow duct as 

 well. The spur and the folds rest on the large lobes of peritoneal cells, one of which 

 is posterior and one anterior. The posterior one surroiimls the spur, upon the ante- 

 rior one, which is the smallest, rests the two folds. The narrow duct is not unusually 

 narrow, while the wide duct or outlet duct is very narrow, not any wider than the 

 narrow duct. The neck of the anterior fold is, where it connects with the nar- 

 row duct, very wide, enlarged, irregular and sigmoid, gradually increasing in size to 

 the anterior fold. Where the two folds join, the fold is always very coiled. The tube 

 forming the bridge is not any wider than the clear canals, but it is less clear or trans- 

 parent, just as in Lumbricus. The canal leading from this bridge into the anterior 

 foM, is straighter, darker, and slightly wider than the two bright tubes which are 

 much coiled and situated more anteriorly and superiorly to the straighter canal. This 

 coiling ceases as soon as the big bend and windings ai'e pas.sed an<l the po.sterior fold 

 is reached. 



The nephrostome is large. The marginal cells in the rosette are only slightly 

 decreasing in size toward the extremities or centripetal marginals. There is a large 

 centripetal protuberance surrounding the inner opening of the duct, as in Lumbricus. 

 as described by Benham, but the centrifugal cells are less regular and more scattered, 

 The centrifugal cells are never hidden by the centripetals as in Lumbricus, and the 

 whole centripetal protuberance is most {irominent seen in whatever direction. The 

 outlet duct enters the fold much closer to the narrow or nephrostomal duct than is 

 usual in Oligoclueta, in fact it connects with the free neck of the anterior fold, close 

 behind the septum. 



The relationship of PnntodrUus JMichaelseni to the other species of the genus 

 is not as clear as we might wish. Beddard's description and noles in his paper, 

 "V. Some new or little known Oligochseta," are the only comparative remarks yet 

 made on the few worms which are grouped under this genus, an arrangement which 

 must be considered as entirely preliminary. The only very characteristic features 

 which connect the six species of the genus is the commencement of the nephridia 

 posterior to somite xii, and the opening of tiie spermduct into the prostate, absence 

 of typhlosole, gra[)e-like sperm-sacs, and no pcnial setir. None of these species 

 have been sufficiently described, an unavoidable fault attendant all species im- 

 mersed in alcohol without previous careful preparation and evacuation. In the 

 following table I have endeavored to compile the characters of the various species as 

 far as I can make out from the descriptions, no spceinuiis for comparison being in my 

 po.ssession. I include here, as suggested by Beddard, the genus PliotudrUus Giard. 

 I have had no access to Grube's descri|)tion of P. l'dturali)>, and have therefore 

 excluded it from this table. 



