THE DEVONIAN FOSSILS OF CANADA WEST. 145 
is yet to be ascertained in how many species this complicated structure 
prevails. We may expect to find by continued search in our Canadian 
rocks, specimens which will enable us to make out the structure of 
these peculiar organs in such species as we have. As yet, I have only 
seen five or six specimens of d. Clara and dA. Maia in which the 
_ spires could be seen, but none are sufficiently perfect to exhibit the 
details. 
In Mr. Davidson’s earlier writings, the muscle called the “ Divar- 
rcaToR’”’ in this article, is styled the ‘‘ Rerracror,” while the “ Oc- 
CLUSOR ”’ is designated the “ Appucror.” But in his recent papers 
in the Geologist he uses both. It appears that the new names, 
*< Divaricator’’ and “ Retractor,’ were devised by Mr. Hancock. 
I shall hereafter, from time to time, as materials are collected, 
publish in this Journal such other particulars of the structure of 
these interesting genera as may seem to be of importance. 
Of this genus, Spirigera, we have, as yet, clearly recognized only 
one species in Canada, but it is, in the opinion of some good paleon- 
tologists, identical with the famous S. concentrica, the type of the 
group. Three species, described in May last in this Journal, which 
have the beak perforated, may possibly belong to Spirtgera, and 
would have been so referred, but at that time I had not made up my 
mind what course te take with regard to the sub-divisions of Athyris. 
The three species in question are not yet generically determined, and 
1 have therefore marked them doubtful thus: <Athyris (/) scitula, 
Athyris (?) rostrata and Athyris (?) Chie. 
SPIRIGERA CoNCENTRICA.—(Bronn, Sp.) 
TEREBRATULA CONCENTRICA.—Bronn, 1829. ArryPa + SpirRi- 
GERA + ATHYRIS CONCENTRICA,—of the generality of authors. 
Sprricera Sprrireroipes, Hall.—Tenth Annual Report of the 
Regents of the University of tne State of New York, p. 153. 1857. 
Fig. 54. Fig. 55. 
Fig. 54. Spirigera concentrica—Dorsal view. Fig. 55. The same.—Ventral view. je 
