﻿ADDENDUM. 



173 



tropical regions, but the Crag shell is by Mr. Jeffreys referred to a species lately obtained 

 from the seas of Japan, L. Jaspidea, A. Adams. I am not able to express any opinion as 

 to the correctness of this identification. My shell differs from L. tenuis in being less 

 slender and in having the front margin more obtuse. 1 



The genus Lingula occurs at the base of the Silurian system, and has preserved a 

 special uniformity of character throughout the whole geological scale, some of the species 

 {L. minima and L. Symondsi) differing, so far as their testaceous remains are a guide, in 

 only a trifling degree from our Crag shell. Moreover, so far as these remains indicate, 

 it has never exhibited any large development of individuals, although there is scarcely 

 a formation in which it has not left some trace of its existence, nor do we see any great 

 variation among the individuals in regard to magnitude. As this genus has existed 

 from the oldest Silurian strata, it can scarcely have escaped encountering a great 

 variety of conditions, and if indications of climate are to be inferred from the presence of a 

 genus in any deposit, what are we to infer from the presence of such a genus as Lingula ? 



ADDENDUM: 



Several new forms having been discovered since the first part of this Supplement 

 was printed, I find it necessary to add another plate with figures and descriptions of these 

 species, and I take this opportunity to introduce some remarks as to other species which 

 have occurred to me since that portion of this Supplement to which their place properly 

 belonged passed through my hands. 



Voluta Lambkrti, J. Sowerdj/. Crag Moll., vol. i, p. 20, Tab. II, fig. 3. 



Mr. Jeffreys in his list refers this shell (with a note of interrogation) to Voluta Junonia, 

 Chemn. 



I have again examined and compared my Crag shell with specimens of V. Junonia in 

 the British Museum, and I find that it differs from Junonia in having a larger pullus, or 

 a more obtuse apex, and when perfect, in the presence of close-set spiral strise, of which 

 there is no appearance in the recent shell. Junonia has also a more expanded outer lip, 

 and is more " emarginate" at the base, and its proportional length of aperture is different 

 from that of the Crag shell. Junonia was figured many years ago by Chemnitz, e Conch. 

 Cab.,' vol. ii, p. 16, pi. 177, figs. 1703 and 1704. Its distribution is somewhat 

 uncertain, but it has recently been found in the Gulf of Mexico. 



1 The muscular impressions as represented in our figure are partly imaginary. 



