256 



THE AMERICAN MONTHLY 



[Aug. 



Astacus lluviatilis 



Uydra 



Hydroids aud polyzoa 



Hydrozoa 



Sertularia 



Zoophytes 

 Clytia volubilis 



U 11 



Plumnlaria setacea 



*"\Vhite ants 



*Sbeep and cattle 



*Swiue 

 Soenaiia variegata 



(( i( 



*Pelobatus fuscus 



*Pbyllodoce 



*Cockioafli 



Cothuruia astaci 

 Dendrosoma astaci 

 Podophrya astaci 

 Kerona polyporuiu 

 Trichodina pediculus 

 Acineta livadiana 

 Ophryodendrum abietium 

 Podophrya lyngbii 

 Ephelota trold 

 Ophryodendrum abietimim 

 Hemiophrya microsoma 

 Ophryodendrum sertularia 

 Acinetopsis rara 

 Acineta creuata 

 Ophryorteudruni belgicum 

 Hemiophrya pusilla 

 Ophryodeudron abietiuum 

 Pedicellatum 

 Trichonympha 

 Pyrosonema 

 Dyuenympha 

 Isotricha 



Ophryscolex purkiujei 

 Balantidiuni coli 

 Ptychostomum 

 Hoplitophrya pungeus 

 Opalina iutestiualis 

 Auoplophrya ovata 

 Nyctotheris ovalis 



A Camera Lucida for Use with both Eyes. 



By ARTHUR M. EDWARDS, M. D., 



NEWARK, N. J. 



When using the camera lucidas, which are on the mar- 

 ket, of course preference is given to that known as Abbe's 

 aud invented by Wollaston. Abbe's is not altogether 

 satisfactory and Nachet's is better. But 1 liave an instru- 

 ment which can be used with both eyes at the same time 

 which seems to be a novelty. And this one besides use- 

 ing both eyes was home-made so that its manufacture is 

 extremely cheap. Besides, it has the novelty of being 

 made by myself, aud can readily be so made by anyone. 



