146 THE AMERICAN MONTHLY [May 



inicleiis could not he observed even ;it'ter tlie most care- 

 ful sc.-ircli rind the applii-at ion (»t' tlic usual reagents. In 

 sonic samples examined all tlie forms under the cover 

 glass were densely vacuolated. 



Family. — ()nytricliid;c. S. K. 



Genus.— Sti{diotri(dia. Perty. 



Si)ecie8. — Stiidiotricha opisthotonoides. (fig. 18.) 



Body elongate; somewhat <dul) sluiped, the anterior 

 two thirds attennnte, three limes as long as the widest 

 part: highly elastic but persistent in sha})e: addicted to 

 cuiving backwards; piM'istome channel-like and extend- 

 ing from tlie apex to the posterior body third and there 

 curved towards the left hand body border, the peristome 

 cilia long aud heavy diminishing in size as they approach 

 the oral aperture; the left hand border of the peristome 

 finely ciliated and bearing a conspicuous undulating 

 membrane, marginal seta) on the anterior half of the sin- 

 istral border and on the posterior border; two oblique 

 rows of small ventral seta' extending- from the sinistral 

 to posterior seta*; contractile vesicle consjticuoiis, located 

 in the })Osterior third and in contact with the left hand 

 boi'der which it extends at each expansion: nucleus, two, 

 ovate and situated one in each body hrilf: locomotion 

 eccentri(^ Size 1-450 inch. 



Habitat- Old infusion of .-Kiuatic plants in ditch water. 



The writer hail under observation tpiitc -i large num- 

 ber of tli's new foi'in and they were all .-nldicted to the 

 habit of luMiding the anterior attenuate body half back- 

 wards as if ill great pain: it was this peculiar habit that 

 suggested its sp(M'ific name. W hile in this act the undu- 

 lating nii'iii bi aiic is thrown out from the body border to 

 a cousidciabli^ (listaiic(\ Tin- wi'itcr has ne\t'i' seen 

 recorded thai an\ of this genus jiossesscd an undulating 

 membrane and ludieves this species stands alone in this 



