386 BULLETIN OF THE 



be spinose, were separated by H. & A. Adams under the name Arene. Their 

 diagnosis was not of the best, and comprised several characters certainly not 

 of generic value. I am unable to see any characters in the subgenus Liotina 

 Munier-Chalmas which should separate it from the typical Arene. 



Another group, which in my opinion belongs 'here, is Lippistes Montfort, 

 based on the Argonauta cornu of Fichtel and MoUer. This is not the Argo- 

 nauta cornu of Chemnitz, as has hastily been assumed by some authors. The 

 latter is apparently an Atlanta or Oxygyrus. Montfort's figure represents a 

 shell which does not appear to differ from the forms named Daronia by Arthur 

 Adams, and Ilaira by II. & A. Adams, the quadration of the aperture in the 

 latter being a merely specific incident due to its sculpture, and probably not 

 permanent in all individuals of the same species. If, however, the disjunction 

 of the latter part of the last whorl be considered sufficient to separate it from 

 Daronia proper, where the whorls, though rolled in nearly the same plane, are 

 contiguous, Ilaira must take its place with Lipjnstes proper, which has this 

 character, while the final term of the series is afforded by Laxispira Gabb, a 

 section which may include Delphinula nitida Verrill, in which all the whorls 

 are lax, and to which D. laxa Say (if not a monstrosity) may also belong. 

 The latter has been referred to the Rudistes by Tryon (Man., II. p. 309), but 

 this must be due to some confusion of types. Mr. Say's original description 

 and very good figure are incompatible with such a reference. There is much 

 more probability that the type of D. laxa was a deformed Natica, as Say him- 

 self suggests. He describes it as a recent marine shell, inhabiting the coast of 

 South Carolina among other marine shells. No suggestion of its being a 

 fossil is anywhere made by Say, nor are any Carolinian Rudistes known. But 

 as he says nothing of its being pearly, and compares it to Natica, it is probable 

 that it does not belong to the group now under consideration. 



Laxispira would appear to be without a varix or thickened ring at the 

 extreme end of the adult coil; but this cannot be positively asserted, as but a 

 very few specimens of these remarkable shells have ever been collected. Tu- 

 biola A, Adams would appear to bear much the same relation to Cyclostrema 

 that Ilaira does to Lippistes. 



The characteristics of the Liotice and their relatives are not those usually 

 made use of for diagnoses. Some Liotice are most brilliantly pearly (e. g. 

 L. fenestrata Cpr., of California) ; others when not perfectly fresh do not show 

 a trace of nacre. Yet even these (Arene cruentata Miihlf. for example), when 

 perfectly fresh and closely examined, show a very well marked varnish of pearl 

 about the aperture. I have not seen any species, when perfectly fresh, which 

 did not show at least a little nacre, though the majority do not show any when 

 dry and " dead." 



Arthur Adams describes the operculum in some Japanese species as horny, 

 hispid, multispiral, and having an external limy layer composed of small grains 

 like beads, spirally disposed. In Arene cruentata I find the operculum solid, 

 thick, multispiral, with hardly a trace of horny matter except at the margin. 

 Externally it is concave, with a small central pit corresponding to a small 



