iy2 University of Texas Bulletin 



The siphonal lobe is divided into two branches by a moderately high 

 and narrow median saddle. Each of the branches is strongly curved 

 with the convexity toward the umbilical side; and they are bifid, the 

 point on the siphonal side being a little longer than that on the um- 

 bilical side. There are two indentations on the umbilical side of the 

 branch. The first la:teral lobe is not as deep as the siphonal one. It 

 is trifid and not quite symmetrical, and the middle point is longer than 

 the lateral ones ; the lobe has two more indentations on each side, and 

 is narrower at the top than in the middle. The second lateral lobe 

 is very similar to the first one, but less deep. The first and second 

 auxiliary lobes are very similar to the lateral ones but less deep, but in 

 the second auxiliary lobe the lateral point on the siphonal side becomes 

 somewhat longer than that on the umbilical side. This character is 

 still more pronounced in the third auxiliary lobe, which thus takes 

 on the aspect of being bifid. The fourth auxiliary lobe is still more 

 asymmetrical and ends in a long point, while a smaller point exists on 

 each side of it, of which the one on the umbilical side is far longer 

 than the other. A fifth and ver}^ small auxiliary lobe exists on the 

 umbilical shoulder. The depth of the lobes begins to decrease from 

 the first lateral, the second lateral being much less deep than the first 

 one, while the first auxiliary is very little dififerent from the second 

 lateral. From the second auxiliary lobe to the umbiJicus the lobes begin 

 to decrease rapidly in depth. The lobe and saddle on the umbilical wall 

 seem to be very simple and rounded, but they could be seen only on 

 immature specimens. 



The median saddle of the siphonal lobe (pi. X, fig. 31) is relatively 

 low, narrower at the base than at the top, where it is notched by a 

 slight indentation. It has also a slight indentation on each side above 

 the base. The external saddle is about twice as high as the median 

 saddle ; it is distinctly curved with the convexity toward the umbilical 

 side. It ends in a large phylloid point and has four short lateral 

 branches. It is narrower at the base than at the top. The first lateral 

 saddle is nearly as large as the external, but it is a little narrower and 

 more delicate. On account of the curvature of the suture it looks as 

 if it were higher than the external saddle. It ends in a large phylloidal 

 point and has four lateral branches. The second lateral saddle is prac- 

 tically equal to the first one in size and shape, but perhaps a little 



