SIXTH, OB OXYXOTN I B \n BB INCH 219 



of tlii- Q ■■■:•'- I G G tnd is 



properly referred 1>\ him to the no p. An error is also shown by the 



: this name foi Middle 1 



! . 

 TIi' - figured bj Wright Lb a large Bhell, about 17"> mm. in diam< 



which has already loel the keel and pile, the abdomen being rounded. The 

 internal whorls of th«' original arc heavily pilated, bul the las) whorl and a half 

 S iwerby's figure i- taken from n verj larg I specimen, and 



the pilations Bbown in the umbilicus indicate a shell with ln-.i \ i«- 1 [olds at 1 1 1 » * Bame 

 hi exist in either Hauer'a or Wright's figures, Wright's descriptions, how- 

 ever, coincide with S • figure, and the old - hell has a com* 

 pletely elliptical aged whorL The Bize at which senility affects the Bhells, and 



oeral chai I these figures, are the Bame as in 6 



Tin- young forms figured by Bauer may possibly be the young of this Bp 

 thej i heavily pilated for the j xynotvm. 



Oxynoticeras Guibali, Htatt. 



Ft I i . 'i Bun. li Mil- I il; 14. 



Amm xxxi., xlii. 



A mm 



keel <>f •' - may begin to disappear in Bome specimens even at the 



: 100 nun. In one Bpecimen of tin- Seraur collection this is accompanied by 



dar and marked lateral deflection of tin- hollow keel, and at tin- Bize of 



180 inin. it had wholly disappeared, and th«- outer whorl bad a very broad 



i lomeu ; the Bides, however, remained convergent and rounded. 



•iinen of thi- Bpecies from Lyme Regis in the M tseum of fJom- 



. which was found associated in the Bame Blab with ( 



I imeter of this Bpecimen is 1 15 mm. The keel is not 



>t on the -. but it had probably 1 n pn 



ihell, and evidently not impaired by age; the whorl and invo- 

 dtered from the adult condition. \ 

 showing the inner whorls had Keen formed by fracture, ind tl utlines ol these, 



the hollow keel, and the amount of involution of the whorl-, are the 



D evidently closely allied to C iln. but, 



by Dumortier which al 

 [< in iy prox 



