I'l Kl-I'll I \' I 



<nrvMlurr.il :i - i e-- cut ird \ with tin- formri. lint \\ r imi-t iv 



i MM.* aculpturelesfl rod, strange u it maj leem, as one of the 



lla much elongated ; in regard to tins agreement with thr 



initial whorl.- >f Xncy/0eera, QlienStedl had ahvadx noticed it. 



l-'rMlii JIiH-Hfifrs. /{iin/linit i- dis; in.irui-hed by ollr-pointcd lateral 



lobes. In order to avoid making a nrw name. /tm-itlinti may be 



lirrr applied. 



AR01 MM \. (^unist. r l\ inn. li^. :>17. 



s PEKISPHINCTES, Waagen. 



Slirll mostly with wi<lr umbilicus, with rounded external si<l-. 

 xruli.tun- roiisistinu mostly of straight, undivided, not nodos e 

 ril>- : margin of aperture simple or with r;irs, with a constric- 

 tion : also isolated constrictions on the inner whorls. Length of 

 body-chamber two-thirds to one whorl, mosth" scarcely embra- 

 cing <>nc circMiinl'rrnicc or i urn. Lolmhir line similar to Stephano- 

 -. ii-uall\ somewhat more deeply notched, with a dependent 

 sutural lobe. Aptyrhns divided, calcareous, very thin, exter- 

 nally u'niniilar. 



The irenus ri't-iii^hinctes embraces the old group of the Planu- 



Itifa. with the exclusion of Mir Liassic forms, which belong to 



W; the geologically oldest species of typical Peri- 



.-//A///'-/rs is P. Mart-insi, from the upper p:irt of the Lower 



Oolite; thr li-enus brandies off in all probability from Stephano- 



-. l>iit the relationship between the two is however not yrt 



fully known. The maximum development is readied in the 



Upper Jurassic J in the rrrtaccous there arc yrt few representa- 



tive which have retained their character in purity, and instead 



numerous di\ er^inu- series branch oil', which must be separated 



-tinct i:-riirra. and which embrace thr majority of the rreta- 



rrims Ammonite-. 



We here placr also aiiot her group provisionally, which perhaps 

 to be elevated into a distinct reniix. T<> l*> -rt./i/i inrtf.* 

 . /itt.. from Stramheru;. which still pn-niis thrtypr 

 of the jjrims x,m,. Strambrri:- form- :irr nllird with a deepened. 

 -month external furrow and stronger -rulptiirr on the bod \ 

 chamber. a> V<,\ inu-rnm ,,tl, //.<, Op]).. K'<>lliL-< //. ( >pp.. .- 7///i/*/f/x, 

 Op|. To thr-r certain forms from the lower Xeocomian are 



