256 A. E. Verrill — Mollusca of the New England Coast. 



relatively shorter and broader and more regularly elliptical than the 

 recent ones, as well as higher and more conical ; they also have the 

 aperture more central. In sculpture the two forms are very similar, 

 but the fossil specimens have the sculpture decidedly coarser, with 

 the radiating lines stouter, more elevated, and more unequal, one 

 sti'onger rib alternating usually with three to five smaller ones, 

 while in E. Ta)tneri no such marked inequality exists. The apical 

 pore and the internal callus are very similar in the two shells, but 

 the pore is perhaps a little larger in the living foi-m. A larger series 

 of both the living and the fossil form might, however, show that 

 they are both variable, and possibly grade into one another. 



Addisonia paradoxa Daii. 



Verrill, these Transactions, vol. v, p. 533. 



Plate XXIX, figures 10, 11, 11a, 115. 



Mr. Dall has called my attention to the remarkable peculiarities in 

 the structure of the animal of the male, which differs widely in 

 appearance from the female (see our fig. 11 J), owing to the fact that 

 the large verge is closely united at base with the right tentacle. 



Additional specimens were taken in 1882, living, at stations 1098, 

 1109, 1110, 1124, in 89 to 040 fathoms; and in 1883, at station 2011, 

 in 81 fathoms, off Chesapeake Bay. 



Choristes elegans, var. tenera Verrill. 



These Transactions, vol. v, p. 541, pi. 58, figs. 27, 27«. 



Plate XXIX, figures 9, 9a, 9&. 



This species was taken in 1882 at station 1096, in 317 fathoms; 

 station 1124, in 640 fathoms; and 1154, in 193 fathoms (one dead). 



At station 1124 about twenty-five living specimens occurred in the 

 empty egg-case of a skate {Raia sp.), in the same manner as those 

 taken in 1881. They were associated with a limpet, PropilkUum 

 pertenue ? Jeffreys, 



Young specimens of various sizes occurred in these instances with 

 the adults. Three of these young specimens are figured on our plate 

 29. The youngest examples noticed coiisisted of about one and a 

 half whorls ; these are very small, white, regularly coiled, with the 

 whoils well-i'ounded and increasing rapidly in size. The apeilure is 

 nearly round and somewhat oblicpie, with the li]) perfectly continu- 

 ous. Tlic uiiibilicus is rather large and open and shows the previous 

 wliorls to the apex. 



