‘the 
320 Mr. J. Morris on the genus Siphonotreta. 
careo-corneous, more solid than Lingula, but closely allied to it, 
and differing from it in having one valve with a slight furrow for 
the passage of the pedicle, as well as some modifications in the 
interior structure of the valves. 
The group of the Siphonotrete, Kut., are arranged by M. 
D’Orbigny, under the families Lingulide and Orbiculidee, in his 
first great division of Brachiopoda, with the following characters 
(Comptes Rendus, vol. xxv. p. 267, Aug. 1847) :— 
Lingulide. A pedicle or exterior muscle passing between the valves ; 
shell corneous ; animal fixed. 
The beaks of both valves hollowed with a furrow for the passage of 
the muscle’. SNA tee ke CLMnguiG, Eaee 
The beak of one valve only with a furrow for the passage of the 
TTMUSCLE Fee te ees Sete eae eae yen Obolus, Eichwald. 
Orbiculide. ‘The muscle passing out by the inferior valve; shell 
free. 
Shell testaceous, perforated ; muscle of attachment pedunculated, 
placed at the summit of the beak.. Siphonotreta*, De Verneuil. 
Shell testaceous, perforated ; muscle of attachment placed by the 
side: of thevbeak’ ..)o4:. Ske. eee Orbicella +, D’Orb. ; 
Shell corneous, not perforated ; muscle pedunculated. 
Orbiculoidea, D’Orb. 
Shell corneous, not perforated ; muscle not pedunculated. 
Orbicula, Lam. 
From the above general remarks, it will be evident that the 
four genera above mentioned cannot properly be arranged in 
the same family of which Siphonotreta is the type, and from 
which the other three are readily distinguished ; im fact, as pre- 
viously observed, they belong to four distinct groups ; Szphono- 
treta being allied to Crania, Schizotreta to Orbicula, Aulonotreta 
to Lingula, and Acrotreta probably identical with Cyrtia. 
I shall conclude these notes with the following brief descrip- 
tion of the new species of Stphonotreta :— 
Siphonotreta anglica. Pl. VII. fig. 1 a-e. 
Shell of a rather oblong-oval form, depressed, marked by the 
fine lines of growth ; surface minutely but concentrically reticu- 
* Mr. W. King places Siphonotreta in the family Craniide. 
+ Orbicella, D’Orb. (Aug. 1847), is stated by Mr. Davidson, ‘ Bull. Géol. 
Soc. France,’ n. s. vol. v. p. 315, to be identical with the genus 7’rematis, 
Sharpe (June 1847). This can scarcely be the case, if both genera are cor- 
rectly described ; for Orbicella is placed by D’Orb. among the hingeless Bra- 
chiopods, whereas Mr. Sharpe describes 7rematis as having a hinge. The 
two diverging plates in the xon-perforated valve of 7rematis are somewhat 
remarkable, as, where they exist in other Brachiopoda, they always form 
internally the margins of the deltidial area, partly protecting the passage for 
the muscle of attachment, and forming the dental processes of the hinge. 
