384 
SUPPLEMENT. 
In Part I. of the present Catalogue (p. 186), 1 erroneously referred 
this species to Actinoceras spheroiddle^ Stokes h 
It may be mentioned that there are two more segments in the 
type specimen of Huronia Portlocki than are figured by Stokes. The 
top part of the specimen being broken off was probably overlooked 
when the drawing was made ; it is now united to the main mass. 
Horizon. Magara Group (Wenlock). 
Locality. Drummond Island, Lake Huron. 
Represented in the Collection by the specimen (No. 33418) 
figured by Stokes. 
Subgenus MELOCERAS ^ 
Cyrtoceras (Meloceras) impotens, de Koninck. 
1880. Cyrtoceras imjmtens, de Koninck, Faune du Calc. Carbonifere de 
la Belgique (Ann. du Mus. Roy. d’Hist. Nat. de Belgique, vol. v.), 
pt. ii. p. 28, pi. XXXV. ff. 8, 8 a. 
Sp. Char. Shell of moderate size, slightly arcuate, increasing 
slowly in diameter. Transverse section circular. Septa rather 
shallow ; wider apart than they are generally in species of this size, 
being 3| lines distant from each other where the shell diameter is 
11 lines. The siphuncle, which appears to be nummuloidal, is 
situated a little excentricaUy, towards the ventral side ; it is rela- 
tively thick. The test is thin, with a smooth surface. 
Remarks. Only one large fragment, consisting of nearly the 
whole of the septate part of the shell, was known to M. de Koninck. 
The species most nearly alKed to C. impotens was judged by de 
Koninck to be his C. dejleccum, which is, however, distinguished by 
its considerably smaller size and eyliudrical siphuncle. 
Horizon. Carboniferous Limestone. 
Locality. Ireland. 
Represented in the Collection by a single example. 
ASCOCERATID.® 3 and LITUITIDiEL 
In Part I. of the present Catalogue ^ (1888), reference was made 
to the important discovery by ^Dr. Gustav Lindstrbm, in the Silurian 
rocks of the Island of Gothland, of the missing part of the shell of 
^ Bigsby, Trans. Geol. Soc. 1824, ser. ii. vol. i. pt. ii. p. 203, and explanation 
of plate xxviii. f. 5. 
2 See Pt. I. of the present Catalogue, p. 269. 
® See Pt. I. of the present Catalogue, p. 246. ^ See su^rh, p. 1. 
® Supplement, p. 334. 
