Family Trochid^e. 
Genus Troclius, Linnaeus . 
TltOCIIUS (SCALiETROCHUS) LINDSTROMI, Sp. 7100, 
(PL viii., Pigs. 1 and 2.) 
Sp. Char. — Shell pyramidal-conical, of more than six whorls, 
with an acuminating sharp spire ; under surface flattened, not 
concave, hut depressed immediately around the columellar 
centre, which is quite devoid of an umbilicus ; whorls concave 
or concavely-biangulate, close sutured ; body whorl with a 
very sharp peripheral edge, dividing the upper superior from 
the inferior surface of the shell, aperture transversely ovate ; 
inner lip sharp, probably bevelled inwards ; surface ornamented 
by obliquely-curved, somewhat rough and irregular, subimbri- 
cating laminar striae. 
Ohs — “ It is with great diffidence the following species have 
been described as belonging to the old genus Troclius. The 
only reason for placing them there is the general exterior shape 
of the shell, it having not been possible to find any evidences 
from the microscopic structure of the shell nor from any traces 
of a nacreous stratum or an operculum. On the other hand 
there are so many genera of shells which have persisted from 
the Silurian age through all the following and so still continue, 
and it may therefore not be thought an impossibility that also 
the Troclii existed already in the Silurian times.” 
So writes Dr. G. Lindstrom* on the Trochidse of the Wenlock 
rocks of Gotland, but the union of the perforate and n on-per- 
forate forms made by this author, seems to me manifestly a 
retrograde movement, more especially when several genera 
have already been proposed for the reception of the perforate 
Troclii, such as Palceo troclius Hall, Eotrochus Whitfield, Flemingia 
de Koninck, and probably Pycnompl talus, Lindst. The entire 
absence of an umbilicus at once separates Troclius lindstrbmi 
from all these genera, and places it more in accord with IVochus 
niloticus, Linn., I do not, however, feel at all satisfied that 
this species, and its probable ally Euonvplialus clarkei , de Kon.,f 
from the Wenlock rocks of Yass can with certainty be referred 
to Troclius. Indeed, the step-like outline of the whorls reminds 
us of Meek’s genus Omphalotroclius , but this is umbilicate, like 
the others mentioned above. On the whole it seems to me 
that we have the indication of a further unrecognised genus, for 
which I would suggest the provisional name of Scalcetrochus.l 
* Loc. cit. 3 p. 14-5. 
f Keek. Foss. Pal. Nouv. Galles du Sud, 1S76, Pt. t, p. 41, t. 1, f- 7, 7 a. 
X Scalas, a flight of steps. 
