196 



HYALONEMA (HYALONEMA) AGASSIZI. 



average 100 : 93. It is to be noted that in the smaller small micramphidiscs the 

 relative breadth of the anchor is, on the whole, in inverse proportion to their size 

 (length) . The curvature of the individual teeth is such that the anchors appear 

 rather broad above and that the end-parts of the teeth come to lie parallel or 

 nearly parallel to the shaft. 



The small micramphidiscs of the other forms appear to be very similar to 

 those of form A. Those of form B (Plate 45, figs. 50-52) are 13.5-31.5 m long, 

 most frequently about 20.1 ix. The limit between the larger and smaller kinds 

 lies, as in form A, at about 29 m- Those of form C (Plate 45, figs. 54-58) are 

 14-30 IX long, most frequently about 18.3 m- The limit between the larger and the 

 smaller kind lies here at about 25.5 m- Those of form D (Plate 45, fig. 62) are 

 13-28 M long, most frequently about 20.1 ix. The small micramphidiscs of form 

 E are 15-34 m long, most frequently about 22.2 fi. The limit between the larger 

 and smaller kind lies at about 24.4 /j. The small micramphidiscs of form F 

 are 15-33 ix long, most frequently about 18.3 fi. The limits between the smallest, 

 the intermediate, and the largest kind of small micramphidiscs of this form lie 

 at about 20.2 n and 25.4 m- 



To obtain a clearer insight into the range and character of the variation 

 of the length of the small micramphidiscs in the four forms of this sponge I 



Frequency 



i Mm 



Form 



3 A 



^ B 



I -- C 



o D 



^ E 



" ^ 



Fig. 7. — Small micramphidiscs. 



