344 G. C. Crick — On Nautilus robusfus. 



not bear an original label, but is numbered 37,010, and has been 

 registered as " Nautilus sp., Inferior Oolite, Les Moutiers, Normandy." 

 As stated in the remarks appended to the original description of 

 the species by Dr, Foord and myself, a figure of the type-specimen 

 was submitted to Dr. Paul Fischer, of the Museum of Natural 

 History, Paris, who kindly replied to the effect that he found no 

 form either in the Museum of Natural History, the Museum of the 

 Ecole des Mines, nor in that of the Sorbonne, which could be 

 identified with certainty with our specimen. He observed that 

 it resembles perhaps some specimens of Nautilus Toarcensis, d'Orb., 

 but that the umbilicus in the latter appears more open and the 

 aperture more dilated, remarks with which we fully concurred. 

 The affinities of the species being nearest to Nautilus Toarcensis, 

 d'Orb., from the Upper Lias, and the specimen numbered 37,005, 

 being apparently specifically identical and bearing an original label 

 indicating that it came from the Upper Lias, it seemed most probable 

 that the new species belonged to the Upper Lias. But there are 

 portions of other fossils preserved in the matrix, among them 

 being a portion of a Belemnite, and a fairly good impression of an 

 Ammonite (see Figures). A plaster squeeze of this Ammonite was 

 taken, and submitted — the specimen being registered as from the 

 " Inferior Oolite " — to Mr. S. S. Buckman for his opinion, and he 

 very kindly replied as follows : — " It is certainly a Faltopleuroceras, 

 and is nearest to Am : costatus nudus, Quenst. Jura, PI. 21, f. 3, 

 which Hyatt made type of his Pleuroceras pseudocostatum, Bull. Mus. 

 Comp. Zool. Foss. Ceph. No. 5, p. 90, 1867. It is also near to 

 the specimen figured by Quenst[edt] Schwab. Amm. PI. 42, fig. 19 

 only as A. costatus nudus ; but this is a different form from that 

 of the Jura. ... 



" Your specimen is exactly identifiable with specimens which 

 are not uncommon in the marlstone of Dumbleton (Alderton Hill) 

 near here [Cheltenham], and at South Petherton — specimens which 

 for want of a better name I have called Faltopleuroceras nudum ; 

 these specimens are characteristic of Middle Lias (Marlstone), and of 

 the Spinati //. That is therefore the date of your N rohustus. . . . 



" Quenstedt called his species nudus as being without spines. 

 Yours has, I think, some indication of spines. I have a specimen 

 very like yours from Mid : Lias, Tilly sur Seuilles, Calvados, 

 and it is well-spined. Both spined and unspined forms occur 

 at Dumbleton, etc., so this point makes no difference as regards 

 horizon." 



The present writer fully concurs with Mr. Buckman's determination 

 of the fossil, and therefore regards the type-specimen of Nautilus 

 rohustus as of Middle Liassic age. 



When the original description of the species was framed it was 

 not possible to give the position of the siphuncle. Fortunately the 

 smaller of the Cheltenham College specimens (the example from 

 Gretton) enables us to supply this deficiency. A portion of the last 

 whorl can be detached and the siphuncle seen very clearly. Where 

 the height of the whorl is 49 mm., its width 56 mm., and the 



