115 
side of which are four sharp ridges besides the one that bounds the 
sides and then he adds, “ it is probable that these ridges diminish 
in number as the shell advances, for the larger specimen (fig. 21 has 
but two in place of four, and these even are lost near the aperture.” 
Bemarls. The specimens belonging to this species in the British- 
Museum Collection prove conclusively that the number of keels does 
not depend upon the age of the shell, as supposed by Sowerby, and 
that the latter included under the name midticarinatus two distinct 
types, one of which will now bear that name, and the other the name 
paucicarhiatus^ bestowed by the present writer. 
De Koninck figures a young individual of this species under the 
name multi carinatus, and in his reference to Sowerby’s figures (Min. 
Conch, pi. cccclxxxii. loc. cit.') he very rightly excludes fig. 2, and 
selects fig. 1 as the type of Sowerby’s species. It may be added 
that the specimen figured by de Koninck agrees with Sowerby’s 
fig. 1 in the number of keels (10) on the periphery, and not with 
fig. 2. 
The septa in this species are very numerous, but irregularly 
spaced ; they are from 2 to 2| lines distant from each other, where 
the diameter of the whorl is about 6 lines, while the last three or 
four septa near the body-chamber are not more than 1| line apart. 
A portion of the body-chamber seen in section occupies nearly half 
a volution, but it is imperfect at the apertural extremity. The 
surface of the test is covered with fine transverse lines of growth. 
Both Giebel and d’Orbigny observed the identity of McCoy’s 
jjorcatus with Sowerby’s midticcninatus (pars), but they appear to 
have supposed that the two figures given by Sowerby represented 
one and the same species. The paucity of keels in fig. 2, as compared 
with fig. 1, is not noticed by them, but Giebel remarks that probably 
T. porcatus is only a compressed fragment of N. muJticarmatus. 
A species is recorded by Phillips under the name midticarinatus^ 
Sow., from Cork and Cumberland ; and as he speaks of it in his (very 
brief) description as possessing manj’ spiral ridges and furrows, 
there is very little doubt that he was dealing Avith the present 
species. 
Horizon. Carboniferous Limestone. 
Localities. Cork, Kildare. 
Well represented in the Collection, which contains (‘‘ Sowerby’s 
Collection ”) the specimen figured by Sowerby in the ‘ Mineral 
Conchology,’ besides other examples. 
