FOURTH, OB CORONICEK \n BR Wdl 



nnl shallow channels, Bhow thi* plainly. Tliej belong to the 



typical variety ol ' B •//</>«//, though the evidence must red incom- 



plete until the adults and young are known. 



Coroniceras orbiculatum, ihvrr. 



. 



Ami,. 



Ami I, 2 



The breadth and crowded aspect of the piles in the Scheppenstadl Bpeciraen 

 mi the fourth and tiftli whorl, and the narrowness of the Bides, resemble the 

 chara the same age in Cor. BucHandi, var. suienturiense, more than any 



other the same genua, The young whorls are much too small in all 



their dimensions, and the volutions too numerous i" ' Bucklandi. The adult, 

 with its prominent I ind with the dorsal broader than the abdominal 



i, shows a remarkable resemblance I rotiforme. 

 I e last sutures <>n the ninth whorl have an even, rounded outline, d 

 the small - gularity of the marginal lobes and the roundness <>i ih-' mar- 



ginal saddles, which are similar t.. I I m the lii'ih volution The 



abdominal • » • » t one half longer than the Biiperior laterals, the inferior 



la by about two Gftba. The saddles and 



however, an- broad and comparatively Bhorl in Cor. latum and in the young 



of other forms of Coroniceras. One specimen which is identical with this in the 



- the abdominal lobe on the eighth whorl to !»• one third 



r than the superior laterals, and the superior lateral saddles are nol quite 



one third longer than the inferior lateral-. 



One <>t' the casts from Balingen measuring '-^ v mm. in diameter had about 

 ten volutio i ncrease in the transverse diameter of the whorl is more uni- 



ni'l gradual than in ( B u On the latter ; 



the ninth whorl the piloa Bhow the approach of old age in the loss "i theii 



I end farther upon the Bides, and are less abruptl) 



doinen, which therefore i- more rounded and prominent than in 

 the adult. The channels have shallower, and finally lose their lateral 



upon the latter half of the tenth whorl. The heel i- >till ..i coi 



iter prominence than in the | 



The breadth of the abdomen mi rosa the genicul 

 than the breadth of the dorsum when measured through the umbilical shoulders 

 on the second quarter of the tenth whorl, and 13 mm less thai the fourth 



• r of tie- - me- vol II I 



lible on th i ter <>i tie- ninth « Inn 1. 



hilt the int. i than ' 



On t! if th-- tenth whorl tin- abdominal lobi 



