140 
NAUTILOTDEA. 
occupied by six rows of closely set, prominent, obtuse tubercles, 
elongated in the direction of the aperture, one row of tubercles of large 
size bounding the back, a double row of equal size between it and 
tbe channel, and three on the sides, which decrease in size towards 
the umbilicus. Surface marked with coarse, squamose, wavy lines 
of growth which are arched backwards in the dorsal [= ventral or 
peripheral] channel. Septa numerous, their edges arched consider- 
ably backwards on the periphery, and slightly so at the sides. 
Siphuncle inch diameter, central. Dimensions — width of 
greatest diameter 3^ inches, width of outer whorl near the aperture 
1 inch.’’ [Armstrong.') 
BemarTcs. There is nothing to be added to the above very accurate 
description. According to Mr. Armstrong this species belongs in 
Scotland to the “ upper division of the Carboniferous Limestone 
series of Clydesdale, to which group it would appear to be restricted, 
no specimens having been observed in any of the lower beds. Good 
external casts are not unfrequently obtained in the limestones of 
Castlecary, Arden, and Garnkirk ; while one or two entire speci- 
mens with the shell preserved have been found in the shale at 
Gare, near Carluke. At this locality as well as at the adjoining old 
workings at Westerhouse, pieces are common which often exhibit 
the siphuncle and the beautiful shell-markings.” There is a fine 
example of this species in the Museum of Practical Geology. 
Koemer institutes a comparison between Pleuronautilus nocloso- 
carinatus and Nautilus Koninchii, d’Orbigny, but the differences 
between these species are too obvious to make it necessary to 
recapitulate them here. 
The nodose character of the ornaments is less marked in the 
German examples of this species than in the Scotch, while, on the 
other hand, the spiral ornaments are more prominent in the German 
examples than they are in the latter. I think there can be no 
question, however, as to the identity of the two forms. 
Dr. Eoemer’s specimens were collected in the Hohenlohe Mine 
(Franconia), the only locality known to him. 
Horizon. Carboniferous Limestone. 
Locality. Westerhouse, Lanarkshire. 
Eepresented in the Collection by several fragments having the 
shell preserved upon them. 
