6 

 GLOSSARY 



Arcuate - bent like a bow (see Fragilaria arcus , p. 38) 



Brackish - having a dissolved salt content intermediate between fresh 

 and salt water. 



Capitate - swollen at one or both ends in valve view (see Caloneis 

 amphisbaena , p. 63) 



Carinal dots - circular or oval pores more or less evenly spaced along 

 the keel, usually appearing as dots or lines (see Nitzschia , p. 90) 



Costae - internal or external linear thickenings of the valve surface 

 appearing as ribs; because of light diffraction, the tapered 

 shoulders of the costae may appear as dark lines (see Cyclotella 

 Meneghiniana , p. 26) 



Facet - (alveola) a circular or hexagonal thin area in the valve sur- 

 face, surrounded by a ridge which may extend internally or extern- 

 ally from the valve surface (see Coscinodiscus , p. 31) 



Frustule - the siliceous diatom cell wall consisting of two separate 

 halves. 



Fusiform - broadest at the middle and tapering at each end, spindle- 

 shaped (naviculoid). 



Girdle - region of the frustule between the two valves. 



Girdle-bands - the two overlapping hoop-like bands which join the two halves 

 of the frustule. They may be connected directly to the valve margins 

 or the intercalary bands. 



Girdle view - side view of the frustule. 



Intercalary bands - hoop-like bands located between the girdle-band and 

 the valve (see Rhizosolenia, p. 22) 



