82 



MICKOSCOPY FOR BEGINNERS. 



teeth. End-lobes broad, often with two teeth ori 

 each end. M. truncata, Fig. 34. 

 I. Each semi -cell divided by deep rounded depres- 

 sions into four tapering, slightly curved arms, 

 the whole desmid having eight undivided arms. 

 M. arcudta, Fig. 35. 



Fig. 35. Micras- 

 t6riaa arcu4ta. 



Fig. SO. Micrasterias 

 dich6toma. 



Fig. ST. Micrasterias Kit- 

 chelii. 



b. Each semi -cell divided by two acute depressions 

 into one end and two side lobes, each side-lobe 

 divided by an acute depression into two short 

 parts, each part divided by an acute depression 

 into two short arms, and each arm with two teeth ; 

 arms of the end-lobes each with two teeth ; the 

 whole desmid with twenty short arms. M. dicho- 

 tomy Fig. 36. 



Fig. SS.-Micraste'iias 6scitans. Fig. 39. Micrasterias laticcps. 



