418 



ANIMAL NATURE OF DIATOMEiE. 



equal to two millimetres. This line is one peculiar to 

 himself; for the line of English measure, which is the 

 smallest of all, exceeds two millimetres in measurernent. 

 Kiitzing makes use of a linear measure with the same 

 notation as that used by Ehrenberg, — three small marks, 

 which usually indicate the millimetre, to the right of the 

 cipher. It would appear that he intends to speak of 

 the same conventional line; at least I arrive at this 

 conclusion from the following comparative table of the 

 extreme length of some species of Navicula, deduced 

 from direct observation, from the cipher of Ehrenberg 

 and that of Kiitzing, on the double supposition of the 

 line being conventionally equivalent to two millimetres, 

 and to the line of the Parisian inch = 2-707 centim., and 

 from Kiitzing' s figures.* 



Navicula ampbisbeena . . . . 0'070 millim. 



Ehrenberg, ^V" ■ • • O'lOO 



Kiitzing, 5V" ... . 0-076— 0-104 



Kiitzing's figure, 0-021 (i^) . . . 0-050 



Navicula cuspidata .... 0070 



Ehrenberg, !■" ... . 0-133 



Kiitzing, sV" ... . . 0-087—0-117 



Kiitzing's figure, 0-0243° (4f«) . . 0-0576 



Navicula appendiculata . . . 0-027 



Kiitzing, s'j 0-037— 0-050 



Kiitzing's figure, 0-0093° (^f») . . 0023 



Navicula viridula 0-047 



Kiitzing, ^" 0062- 0-084 



Kiitzing's figui-e, 0-0192 (Jf ) . . . 004.57 



Navicula gracilis ...... 0-054 



Kiitzing, jV" 0-076—0-104 



Kiitzing^s figure, 0-0207 (if) . . 0-049 



Navicula ?najor ...... 0-335 



Ehreuberg, J"' 0-333 



Kiitzing, ^"' . . . 0-222—0-300 



Kiitzing's figure, 0-058 (i^S) . . 0130 



Navicula oblonga . . . . 0-135 



Ehrenberg, tV" 0166 



Kiitzing, t\"' 0-180—0-246 



Kiitzing's figure, 0-0466 (*}«) . . . 0-110 



It results from this table that the ciphers of Kiitzing 

 express, in fractions of a line (equal two millimetres), 



* In the present translation the decimal numbers indicate millimeters or 

 parts when not otherwise marked, and .parts of a line are given in common 

 fractions with the sign "'. — Ed. 



