256 



THE AMERICAN MONTHLY 



[Aug. 



Astacus fluviatilis 



Hydra 



Hydroids and polyzoa 



Hydrozoa 



Sertularia 



Zoophytes 

 Clytia volubilis 



U (I 



Plumularia setacea 



*Wliite ants 



*Sheep and cattle 



*Swine 

 Soenuria variegata 



*Pelobatus fuscus 



*Phyl]odoce 



*Coekroach 



Cothurnia astaci 

 Dendrosoma astaci 

 Podophrya astaci 

 Kerona polyporum 

 Trichodina pediculus 

 Acineta livadiana 

 Ophryodendruni abietiuni 

 Podophrya lyngbii 

 Ephelota trold 

 Ophryodendrum abietinum 

 Hemiophrya microsoma 

 Ophryodendrum sertularia 

 Acinetopsis rara 

 Acineta crenata 

 Ophryodendrum belgicum 

 Hemiophrya pusilla 

 Ophryodendron abietinum 

 Pedicellatum 

 Trichonympha 

 Pyrosonema 

 Dynenympha 

 Isotricha 



Ophryscolex purkinjei 

 Balantidium coli 

 Ptychostomum 

 Hoplitophrya pungens 

 Opaliua intestinalis 

 Anoplophrya 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 

 and invented by Wollaston. Abbe's is not altogether 

 satisfactory and Nachet's is better. But I have an instru- 

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

 whicli 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, and can readily be so made by anyone. 



