372 DESCRIPTION OF {^Polygosimca. 



Gallionella lineata. — Cyliudi-icul, tlie ends couucctiug tliem together 

 {ihv junction surfaces) comiDressed (fig. 128.) The lines on the surhiee of 

 the segments are transverse, relatire to theii' longer diameter ; the 

 endochrome yellow or green. A single chain consists sometimes 

 of 1200 to 4000 segments, forming a chain two to tliree inches in 

 length; length of frustule 1- 1400th to l-430th. Marine 



The Me'osira lineata (Kiitz.) — Adduced as synonymous with 

 Gallionella lineata (E.) is described as having smooth segments con- 

 joined in pairs; and, in the illustrative figure, no hnes, save some 

 few very delicate ones in the central portion of each frustule, are 

 exhibited, like those in Ehi-enberg's drawing. 



G. numnmloides (E.) — Resembles the preceding species ; but each 

 frustule has its ends convex, and near each of them a Kne, less 

 strongly marked than the central one. The convex ends render the 

 segments almost globular ; the latter, also, are smooth ; their con- 

 tents yellowish-green when drj^, but brown when recent. Diameter 

 l-1700th to l-860th. Sea or brackish water. (P. 14. f. 14, and 

 wood cuts.) 



(3 



G. varians = Melosira varians (Ealfs.) — Joints cylindrical, with 

 flat ends ; when separate, they rest upon theu" ends and appear like 

 coins ; and in such a position, with a high power, delicate radiating 

 striae may be seen (as in fig. 131.*) Contents yellow or gi-eenish. 

 Size l-2200th to l-480th. Fossil and living; the former constitute 

 the principal part of the earthy deposits of white powder used in 

 polishing silver plate. 



G. distans. — Segments smooth, short, cylindrical, plane and trun- 

 cate on the junction siu-faces ; with two sulci or furrows, separated by 

 a more or less considerable interval (distant.) Seg-ments closely 

 conjoined ; then- two diameters equal, or that in the length of the 

 chain double the other. Diameter 1 -3456th to 1 -864th. 



G. sulcata. — Segments short, cylindrical , about equal in their two 

 diametei-8 ; ti-ansversely striped near each jimction-surface, leaving a 

 clear central interspace ; surface of end view, M'ith lines radiating 



