140 



GEODIA AGASSIZII. 



maximum averages (per cent) in a commensurate manner, the number, different 

 in each case, with which the general maximum average nmst be multipUed to 

 make the product 100 mm. was ascertained by dividing 100 mm. by the general 

 maximum average of the dimension in question (II). With these numbers, 

 which are given in III, the deviation of each dimension from the means (V) was 

 then multiplied. The product thus obtained is the percentage (commensurate) 

 deviation given in VI. 



To bring out more clearly the significance of the commensurate numbers 

 given in VI, I have represented the variations of the spicule-dimensions ex- 



I 



II 



III 



IV 



Spicule-dimensions 



General maximum averages. 



Number with which to multiply the general 

 average dimension (col. II) to make it 100 mm. 

 (100 mm. divided by the number in col. II). 



Averages of the three largest dimensions measured of the large am- 

 phioxes, the orthoplagiotriaenes, mesoprotriaenes, anatriaenes, and 

 sterrasters; and maximum dimensions measured of the small dermal 

 amphioxes and the oxyasters. 



A 



Station 

 2886 



B 



Station 

 2887 



C 



Station 

 2978 



D 



Station 

 3088 



E 



Station 

 3168 



F 



Station 

 4193 



G 



Station 

 4199 



H 



Station 

 4228 



I 



Station 

 4551 



Large amphioxes 



length mm. 



3.9 



25.65 



3.4 



3.8 



4.1 



4.3 



4.2 



4.6 



3.8 



3.2 



3.8 



thickness H 



86.3 



1158.75 



75 



93 

 340 



111 



76 



89 



87 



79 



74 



93 



Small dermal amphioxes 



length /( 



34.2 



292.4 



480 



270 



360 



290 



390 



290 



330 



330 



thickness /' 



9.06 



11037.5 



12 



10 



8 



10 



7 



10 



8 



8.5 



8 



Orthoplagio- 

 triaenes 



rhalidome 



length mm. 



3.39 



29.5 



3.1 



3.1 



4 



3.6 



3.9 



3.6 



3.7 



2.5 



3 



thickness A" 



115.44 



866.2 



103 



110 



139 



120 



132 



92 



102 



98 



143 



clades 



length li 



490.89 



203.72 



467 



507 



483 



493 



483 



520 



540 



497 



428 



Mesoprotri- 



aenes 



rhabdome 



thickness 



25.11 



3982.48 



20 



27 



34 



26 



28 



19 



30 



21 



21 



clades 



length H 



161.78 



618.13 



120 



180 



250 



143 



178 



95 



203 



145 



142 



epirhabd 



length fi 



140.33 



712.59 



110 



150 



192 



125 



136 



80 



268 



109 



93 



Anatriaenes 



rhabdome 



thickness H 



32.56 



3071.26 



29 



35 



33 



31 



32 



31 



40 



36 



26 



clades 



length !i 



118.11 



846.66 



67 



133 



140 



98 



145 



123 



120 



130 



107 



Large oxyasters 



total diam- 

 eter /( 



24.22 



4128.44 



21 



22 



23 



25 



26 



24 



20 

 97 



31 



26 



Sterrasters 



length /< 



103.56 



965.66 



96 



102 



111 



118 



109 



94 



98 



107 



breadth fi 



88.56 



1129.24 



82 



88 



94 



94 



94 



82 



85 



88 



90 



