1894.] certain External Parts of Palaemon serratus. 



239 



plained at first sight, unless it be due to difference in habits of 

 locomotion above referred to. 



The subjoined table furnishes the necessary data for constructing 

 approximately the curve of each of the separate organs. 



The Roman numerals in the first column refer to the organ 

 described above under the corresponding numbers on p. 235 ; the 

 second column contains the number of animals out of the whole 

 sample of 1000 in which a measurement of the particular organ 

 was made ; the third column contains the median value ; and the 

 fourth the " probable error " or quartile deviation from the median 

 of each organ expressed in thousandths of the body length ; the 

 fifth and sixth columns refer to the same animals after subtracting 

 from their number thirteen individuals in which the rostrum or 

 telson was deformed, and for these the arithmetical mean and prob- 

 able error (obtained by finding the mean error and multiplying it by 

 O845) are given. 



All the figures in columns 3 to 6, inclusive, represent thousandths 

 of the body length, except those standing against organ No. I (the 

 body length itself), which represent millimetres. 



VOL. LY. 



