FOURTH, OR CORONICERAN BRANCH. 187 



outline, and the pilas are similar. As a whole these four specimens differ from 

 Cor. Sauzeanum, var. Gaudryi, in having a shallower umbilicus and a somewhat 

 greater number of whorls in proportion to the size of the shell. One specimen 

 from Semur is intermediate in characters between the German specimens, and 

 the true Sauzeanum, var. Gaudryi. The Semur specimens also differ in the depth 

 and groove-like aspect of the channels, and the almost sunken aspect of the keel 

 on the casts. The prominence of the genicular reminds one of the fifth whorl of 

 Sauzeanum, var. Gaudryi. 



Both specimens from Semur have similar sutures. The ventral lobe is deep, 

 the superior lateral saddles and lobes very shallow and broad, the inferior lateral 

 saddles very prominent, and the inferior lateral lobes obtuse. The marginal lobes 

 are more evenly distributed than in the German variety. The sutures on the 

 seventh whorl have an abdominal lobe from one half to two fifths longer than 

 the superior lateral lobes, and the inferior lateral saddles exceed the superior 

 laterals in the same proportion. Both in fact approximate to Cor. Sauzeanum, var. 

 Gaudryi, by their sutures. In the German specimens the lobes and saddles show 

 about the same general proportions, though the inferior lateral saddles are much 

 broader, and the inferior lateral lobes deeper, and acute instead of obtuse. There 

 is a large specimen in Professor Quenstedt's collection from Bodelshausen 

 (No. 10673), which is similar to these, but unfortunately the name of this was 

 not noted. 



The keel is quite prominent at the earliest period observed on the first 

 quarter of the fourth whorl, but the channels are hardly discernible. At this 

 period the channel ridges are not developed, and the tuberculated geniculse are 

 high upon the sides. When the channel ridges are distinguishable on the fifth 

 volution, they are continuous. The keel loses its prominence after the channels 

 deepen upon the latter part of the fifth, and the early part of the sixth whorl. 

 The pilse in the young are more numerous than in the adult. 



The largest specimen from Semur measured 348 mm. in diameter, and had 

 about eight and a half volutions. The pike retained all their adult peculiarities 

 and original sharpness, and the quadragonal form of the whorl was also un- 

 changed. The channels were, however, broader and shallower than in the adult. 

 The approximation of this form in aspect and characteristics to its morphological 

 equivalent, Cor. lyra, is so close, that only the most careful study can show them 

 to have been distinct. The young of these two species are quite different at all 

 stages, and can generally be readily separated. 



This species has always the broad abdomen of Sauzeanum and its spinous 

 tubercles, and the young are not so stout as in Cor. lyra. In the succeeding 

 stages the young of lyra rapidly changes from divergent to parallel sided, and 

 then to a convergent sided whorl, whereas in this species the development is 

 much slower. The later stages (Plate VII. Fig. 8) are similar in form to lyra 

 when quite small (Plate IV. Fig. 9). The geniculse usually cut up the channel 

 ridges into waves, and, though not invariable in the species, this occurs so gen- 

 erally as to be a useful distinction, and is evidently of genetic importance in the 

 series. The resemblances of the young to the adult of kridion and the young of 



