﻿463 



specimen, the original of Fig. id, it is about 75 mm. in length along 

 the median lateral line from suture to aperture. The transverse 

 diameter of the septal floor of this given by Saemann in Fig. id\$> 

 29 mm., the ventro-dorsal diameter in the median plane being 

 24 mm. 



The aperture at this stage spreads laterally, slightly flaring but 

 without any preceding constriction. The hyponomic sinus of the 

 aperture was not preserved, but judging from the lines of growth in 

 both species it was broader and perhaps shallower than in angu- 

 latum. In the larger specimen, the original of Fig. ic, the living 

 chamber was measured along the umbilicus, it being incomplete. 

 The whole diameter of this shell, consisting of nearly four and three- 

 fourths volutions, when complete was over 112 mm. 



The length of the living chamber measured along the inner part 

 on the umbilical line, corresponding to the line of involution, was 

 about 75 mm. As estimated by measurements corresponding to 

 this along the median lateral line to a point opposite the termina- 

 tion of the inner line of measurement, this living chamber was cer- 

 tainly over 100 mm. in length. The transverse diameter of 

 the venter of this living chamber at 35 mm. beyond (orad) the 

 septal floor was 34 mm. without the shell. The shell would increase 

 this to between 2 and 4 mm., according to the place of measure- 

 ment, whether between or on the ridges. There are well-marked 

 narrow ridges or costae at more or less irregular intervals on this 

 shell with coarse lines of growth between them. These ridges are 

 not perceptibly reflected on the cast of the interior as in angulatum, 

 even in the young stages of one specimen, but in another they are 

 faintly shown on the cast of the side of part of the third whorl. 



I have been entirely unable to find the usual marks on the ex- 

 terior of the siphuncle of this species, or any other similar form 

 which usually accompanies the short funnels of ellipochoanoidal 

 forms, but Holms and Schroeder's statements are specific, and they 

 have had better opportunities for their studies, so that I merely 

 suggest a doubt with regard to the structure of such siphuncles as ap- 

 pear in this species and which have usually been described as ari- 

 nulated. The contact furrow is well marked in the neanic stage 

 and in ephebic and metaphebic substages, but in the paraphebic 

 stage it is perceptibly lessened and shows a decided tendency to 

 disappear on the free whorl. The dorsum was distorted near the 

 apertural end so that the exact amount of this diminution could not 



