RHYNCHONELLID. 171 
also a young Rh. Wilsoni; and that he has likewise examined the original figure and 
described specimen of Hem. spheroidalis, M‘Coy (‘ Brit. Pal. Foss.’), in the Cambridge 
Museum, and found it to be a small variety of R. Wilsoni ; the specimen being from the 
Aymestry Limestone of Botville. 2. crebricosta, Sow., from the Llandovery of Tynewydd 
(figured in the ‘Silurian System’), is evidently a crushed specimen of 24. Wilsoni, as any 
one can see by a glance at the original specimen preserved in the Museum of the 
Geological Society. Rhynchonella (Hemithyris) Davidsoni of M‘Coy appears, both to 
Mr. Salter and myself, to be only a variety of RA. Wilsonz, with fewer and larger ribs. I 
will describe it separately, but as a named variety of the last-mentioned species.’ 
Position and Locality. Although Viscount d’Archiac, M. de Verneuil, and some few 
other paleontologists, have given the range of this species from the Upper Silurian to the 
Devonian inclusive, it may be here stated that its range has not, I think, been hitherto 
satisfactorily ascertained beyond the Llandovery, Wenlock, and Ludlow periods. In his 
paper on the ‘Parallelisme des depots Paléozoiques de l’Amérique Septentrionale avec 
ceux de !Europe,* M. de Verneuil states that 7. Wilsoni in general belongs to the 
Upper Silurian, and that it is represented in the Devonian system by a species with 
finer and more numerous ribs. At p. 392 of the same author’s ‘ Description of the Fossils 
of the Rhenish Provinces,” as well as at p. 88 of the second vol. of the ‘ Geol. of Russia,’ 
Rh. Wilsoni is said to occur in the Devonian Limestone of Néhou, in Normandy; and 
it cannot be denied that externally the Néhou specimens very much resemble externally 
some varieties of the Silurian shell; but I ascertained that their interiors presented 
constant modifications, which warranted Alcide d’Orbigny in giving to the Devonian 
form the designation of svb-Wi/soni. In vol. ix, pl. xin, of the second series of the 
“Annals and Mag. of Nat. History,’ for May, 1852, I carefully represented the 
interiors of both forms, from specimens collected by myself in England and the 
Continent. 
It occurs in the Upper Ludlow at Brockton and Burton; Delbury, Salop ; Dafaddfa- 
Uchaf, south-west of Hazle, Woolhope ; Hales End and Brock Hill section, near Malvern ; 
in various places in the Woolhope district, Usk ; New Hall, Builth, etc. 
In the Aymestry Limestone, at Sedgley ; Botville ; Church Stretton, Aymestry, Anker- 
dine Hill, Abberley ; Llanbadoc, &., in the Usk district. 
In the Lower Ludlow, St. Ishmael’s Church, Dale, Callow Farm, Hill End, 
1 At p. 87 of the ‘Geology of Russia’ M. de Verneuil observes—“La forme remarquablement 
gibbeuse de la 7. Wilson, par suite de laquelle les plis des deux valves tombent presque perpendiculaire- 
ment les uns sur les autres et rendent les bords trés obtus et a peine angulaux, la font facilement reconnaitre 
au milieu de ses analogues, qui, au reste, ne sont pas nombreuses. Ia plus voisine, sans contredit, est celle 
que Mr. Sowerby a décrite sous le nom de Aérypa spherica (Rh. Davidsoni), et qu’il nous parait méme im- 
possible de distinguer par aucun bon caractére.”’ . 
2 «Bull. Soc. Géol. de France, 2nd ser., vol. iv, 1847. 
3 «Transactions of the Geol. Soc. of London,’ 2nd ser., vol. vi, 1841. 
