262 DESOEIPTITE OATALOQUB 



The growth is very regular and there is no growing over of 

 the perithallium through the hypothallium. In section the cells 

 are 12-14 fi x 20-25 p.. The tetraspores lie in a number 

 of concentric 7,onea in the tissues and are 50-60 fj. by 70-80 yu. 



HoEizoN. — Ceuoraanian. 



Locality. — St. Pat erne, Sarthe, France. 



Type. — ralseontologioal Museum, Old Academy, Munich. 



Eothpletz considers that this species should be placed near 

 L. aniphiroceformis, L. mimmuliticam, L. ramosissimum, and 

 L. raeemus, because of the size of the cells, though in its 

 outward form it diifers from these. 



Iiithothamnium turouicam, Eothpletz. 



1801 Lithothamnium turonicum, Rothpletz, ZeitscLr. deutsch.geol. 

 Ges., vol. 43, p. 313, pi. xv, fig?. 9, 13. 



Small, dichotomously branching form, the branches 3 mm. 

 thick b}' 12 mm. long. When broken across the concentric 

 banding is visible to the naked eye, aud these concentric rings 

 are the tetraspore zones. Cells 9-10 fi by 12-15 /j, and in the 

 hypothallium up to 30 /< long. Tho tetraspores are 30-35 /a 

 wide and 75 ^ high. 



HoKizo.v. — Turonian. 



Locality. — Beaussct, Var, France. 



Type. — Palaeoutological Museum, Old Academy, Munich. 



Both the external shape and the internal cells separate this 

 immediately from L. cenomanicum, while the other forms to 

 which it has an external likeness have not been studied by 

 means of sections, so that this form stands rather isolated. 



Iiithothamnium ampliiroaeformis, Eothplelz. 



1 891 . Lithothamnium amphiroaformis, Rothpletz, Zeitschr. deutsch . 

 geol. Ges., vol. 43, p. 314, pi. xv, tigs. 10, 14. 



Very delicate cylindrical branches, dichotomously divided, and 

 only G'6 mm. in diameter. The cells are 12-15 ^u wide and 

 20-30 n long, and in the hypothallium up to 100 fi in length. 

 No tetraspores or conceptacles have been recognised. 



The fact that the cells are so muoh larger in this form than 

 in L. turonicum, although it is externally of smaller size, 

 precludes the likelihood of this species being a juvenile stage 



