pees Wage 
FOURTH, OR CORONICERAN BRANCH. oul 
respect. A subsequent re-examination and remeasurement of all specimens in 
the Museum of Comparative Zotlogy has shown that the average length of the 
abdominal lobe for nealogic and adult shells is considerably over one third longer 
than the superior laterals. The sutures also vary from the comparatively simple 
margins, with solid looking and very slightly indented saddles, to the extreme 
forms figured in our plates and by Quenstedt. 
Var. C. 
Plate IV. Fig. 9-11, 15, 16. 
In this variety the channels are slower in reaching their full development, and 
the pile are not so prominent, but are more numerous and conform more closely 
to the shape of the whorl. The whorl is altogether flatter, and increases some- 
what faster by growth than in variety B. The channels are hardly perceptible 
on the fourth volution, and in consequence of the smaller size and want of prom- 
inence in the geniculx, the abdomen has at the same time more prominence than 
in variety B. These characteristics are more or less variable. Thus individual 
specimens may resemble variety A in some characters, or variety B in others. 
In a specimen of variety C, Plate IV. Fig. 15, 16, senile characters begin to be 
apparent upon the second quarter of the ninth whorl. The pile are still slightly 
tuberculated, the abdomen though much narrowed is still comparatively broad. 
In a specimen of variety B, at same time the abdomen had become narrow, the 
pila had lost not only the tubercles, but also the genicule, being in their second 
stage of obsolescence. A specimén in the Museum of Stuttgardt, from Gép- 
pingen, measuring 440 mm. in diameter, showed more pronounced senility. ‘The 
sides were exceedingly convergent, the pila obsolescing, the abdomen elevated, 
though the channels and keel were not much changed. In another of the same 
diameter the channels were obsolete, the keel a low broad ridge, the pilee reduced 
to broad lateral folds, and the sides very convergent. In the large specimens 
figured by Quenstedt,' if the figures are accurate, the keel, channels, and lateral 
ridges are persistent. 
In the Museum at Semur is a fine suite of specimens named Vereigetorix, 
Reynés. These specimens did not show senile decline as early as is usual in this 
species. One at the diameter of 525 mm. still retained the pile and the chan- 
nels, though the abdomen had become much elevated. This specimen was dis- 
torted by lateral pressure, so that the transverse dorsal diameter was shorter than 
the abdominal. 
Wright’s figure? seems to be identical with this species, and the more com- 
pressed specimen figured on Plate IV. seems to be intermediate between my Cor. 
lyra and Cor. Gmuendense. do not remember having seen any such forms myself, 
nor are any English specimens mentioned in my notes. 
1 Amm. Schwib. Jura, pl. vii. 2 Lias Amm., pl. iii. 
