imperfectly-defined Species of Jurassic &c. Nautili. 401 



biting the inner volutions. Transverse section of the whorls 

 wider than high. Septa very slightly curved upon the sides, 

 and forming a slight sinus upon the periphery. Siphuncle 

 placed a little below the centre. Ornaments of the test con- 

 sisting of numerous, prominent, obtuse ridges, separated by 

 interspaces about half their own width. These ridges are 

 about 2 lines wide on the periphery, where they form a deep, 

 narrow, back wardly -directed sinus. 



Remarks. This species differs from N. radiatus by its more 

 compressed form and the much finer ornaments of the test. 

 Moreover, N. neocomiensis is stated by d'Orbigny to have 

 been found only in the middle beds of the Neocomian, while 

 N. radiatus was peculiar to the Craie glauconieuse (" Craie 

 chloritee" of d'Orbigny and the older authors), none being 

 found in the intermediate beds. 



N. squamosus, Lange (Schlotheim), and N. varusensis,' 

 d'Orbigny, are placed in the synonymy of the present species 

 on the authority of MM. Pictet and Campiche. Of the 

 former those authors affirm that Quenstedt was quite in error 

 in supposing it to be identical with the neocomiensis of 

 d'Orbigny, the N. squamosus of Lange being a smooth species 

 from the Jurassic rocks of the neighbourhood of Baden. Of 

 the latter {N. varusensis) the same authors remark that the 

 short description given of it by d'Orbigny indicates no appre- 

 ciable difference between it and neocomiensis. 



Stoliczka * held that the Nautilus Kayeanus of Blanford 

 was identical with N. neocomiensis, having arrived at that 

 conclusion by a comparison of actual specimens of the Euro- 

 pean with the Indian fossils. He finds, it is true, that 

 Pictet's specimens have generally a smaller number of septa 

 (about 15 to a whorl) than the Indian ones, but the latter 

 agree perfectly w T ith d'Orbigny's original figure of N. neoco- 

 miensis, and, he adds, an equal number of septa, about 20, 

 are to be observed on specimens from Escragnolles, the typical 

 locality of d'Orbigny's species. 



Horizon. Neocomian. 



Localities. Grasse, Escragnolles ( Var) , France ; Neuchatel, 

 High Alp (Sentis), Appenzell, Switzerland. 



7. Nautilus hunstantonensis } sp. no v. 



Sp. char. Shell moderately inflated, slightly compressed on 

 the sides, rounded on the periphery, widest part of the whorls 

 in the umbilical region. Umbilicus small, deep, with steeply 



* Mem, Geol.Surv. India, Pal<sont. Indica. — Cretaceous Cephalopoda 

 of Southern India, 1866, p. 210. 



