DOWLING. 
SILUKIAN FOSSILS 
43 F 
Surface apparently .smooth. 
Spiralia directed towanl the dorsal side (Schuchert) ; jugum, muscular 
impre.s.sions, and hinge dentition unknown. 
Dimen.sions of a typical and average spocinien (from the Winisk 
river) : ma.ximurn length, slightly over eight millimetres ; greatest 
width, eight mm. and a half ; maximum thicknes.s, four mm. 
Two small loo.se Mocks of limestone from or near the mouth of the 
Winisk river, collected hy Mr. W, Mclnnes in l!l03, are almo.st exclii- 
.sively composed of nearly perfect shells of this species, many of 
which have the spiralia, or internal spiral cone.s, preser\ed. Some 
of the best of these specimens have been examined by .Mr. Charles 
Schuchert, of the IT. S. National Museum, who write.s as follows in 
regard to them in a letter dated March 9, 1901. “The spiral cones 
in the M’inisk shell are directed toward the dor.sal .side, but 1 cannot 
see the jugum. For the present T would refer it to Tn 
e.xternal characters it is very near to (!. suhomla (Sowerby) but the 
dillorence in the spiralia will distinguish them, as the latter has the 
cones inwardly or medially directed. This difference is certainly of 
specific value, but for the present I should not regard it as of generic 
importance, as dilTerent genera of tho Atrypidie have the spiralia 
directed either laterally, medially or dorsally.” 
Fkwan liver, foot of portage road, one specimen; Fawn river 
(or branch of tho Severn), thirteen .specimens ; all of which are pro- 
bably referable to this sj>ecie.s, though none of them show any vestige 
of the, spiralia or of any of the other characters of the interior of tho 
valves. They are, perhaps, a little more convex proportionately than 
the typical form from the Winisk river. The sinu.s in each of their 
ventral valvc.s seeni.s to be a little more developed. Tn the.se respects 
the speoiniens from the Winisk are more like the Atiypu compy’esm of 
Sowerby, and those from the Kkwan .in l Fawn river.s more like the 
/I. of t he same author, both of which are now regarded as 
form.s of Gtassui .snhovata. 
Spiriff>r crutpiix { Ilisinger. V'^ar. 
Kkwan river, middle rapid : one good .specimen of a .«mall radiatoly 
ribbed Spiri/er, that is apparently similar, in size and general shape, 
to the S. a.s do.scribed and figured by Kuropean and American 
paheontologists, but wliich has narrow and angular, not wide and 
rounded riVis, 
