No. 478] 



OHIO NAIDID.E 



685 



of Cornell University, an.l the ^luseum of Comparative Z.x.loirv 

 of Harvard Cniversity, in the loa,, of hteralinv o.herwi.r Inar.v.'.i- 



the ^Museum of Comparative Zoolofjy for iiotin^- certain i-eftMcnces. 



The studies of the variotis species ^vere maile primarily from 

 living specimens, all figures having been drawn with the aid of 

 the camera lucida at the magnification noted in each instance. 

 The most satisfactory method was that of transferring the Naid 

 from the culture hv tneans of a pipette to a watch-glass and sub- 

 se(iuentlv to a drop of water on a slide, then placmg over the drop 

 a cover-glass the margm of which was supported bv an extreinelv 

 thin wooden wedge. After a time the specimens, without tmdtie 

 compression, would become quiet and outline drawmirs could hv 

 made with the camera. Specimens to be mounted were fixed 

 with hot sublimate-alcohol fsiil)hmate 10 u".. absolute alcohol 

 100 cc distilled water 100 c( u ta i i 1 _> < t um I m borax- 



tioned were stained in hiematin I A (Apathv) or in iron-ha'ma- 

 toxvlui flleidenhain) after fixation in cold sublimate-alcohol. 

 The index of refraction of balsam approaches so doselv the 

 refraction ot the transparent seta^ that m order to studv them 



make (•.■Imcra liici<la drawings of the x'ta- in the dor>al and ventral 



VUv \aidi(he are distmo-mshed from the other families of the 

 ( )li<i()cha>t:> primardv bv the tact that their normal method of 

 repm.hiction is bv means of buddimr. and that complete inter- 

 stgmtntal di^stpimtnt. im i>h nit Ihe dosdx ilhtd f umK 

 .^^:olosoniati(he an unliout <l,.MpnnHU. md xn n.u dk of nm. h 

 smaller size. Furthermore, the proence ot coloicd oil di()p> 

 to<rether with tlie al)sence ot biimcmate ^eta' air diaiactcr. winch 



