128 PROCEEBINGS OF THE MALACOT,OGTCAL SOCIETY. 



Nauxilus triiuANus, J, clc C. Sowerby. 



Nautihcs urhanus, J. de C. Shy. — Mineral Concliology, 1843, vol. vii. 



p. 36, pi. Dcxxviii. Edw. — Mon. Pal. 8oc. 1849, p. 46, 



pi. iii. tigs. 2a, 2b ; pi. viii. fig. 4. J. de C. Sby. — Dixon's 



'' Sussex," 1850, p. 228. Foord.— Cat. Foss. Coph. 



British ]\Luseiim, 1891, part 2, p. 320. K. B. Newton.— 



Syst. List Edwards Coll. Britisli Museum, 1891, p. 291. 



Distinguished from N. centralis by its flattened form and the greater 



length of its aperture ; and from N. regalis by its open umbilicus, 



the truncated extremities oil the dorsal lobes of the septa, and its 



discoidal shape. Lines of growth prominent and strongly decussated. 



Rare. 



Formation. — London Clay. Localities. — St. Katharine's Docks, 

 Sheppey, near Whetstone, and near Chalk Earm. 



Genus HERCOGLOSSA, Conrad. 



American Journal Conch. 1866, vol. ii. p. 101. 



Type. — Nautilus Parkinsoni, Edwards, Mon. Pal. Soc. 1849, p. 49, 

 pi. vii. 



" Nautiloid ; septa angular and linguiform ; apex of the angle, or 

 tongue-shaped lobe, not contiguous with the adjacent septum; siphon 

 largo or moderate, situated within the centre or between the 

 middle and inner margin, and not dorsal or funnel-shaped, but 

 tubular and gradually tapering. — Nautihis orbiculatus, Tuomey. 

 This genus contains Aturia Matthewsoni, Gabb, and perhaps 

 another from New Jersey. Eocene species, Nautilus Parkinsoni, 

 Edwards. An undoubted species of Aturia, which is characterized 

 by the funnel-shaped dorsal siphuncle, has not yet been found below 

 the Eocene. Mr. Gabb does not describe the siphuncle or its position 

 in his shell, and I have been guided only by the angles of the 

 septa not being contiguous and its geological position in the Cretaceous 

 formation. If Mr. Gabb will compare the specimens from Division A 

 with those in Division B, and note tlie differences, if any, especially 

 in the siphon, it will be important both in a stratigraphical and 

 conchological point of view. My attention to this subject has very 

 recently been called by the account of N. Parkinsoni in Edwards' 

 Monograph of the Eocene Cephalopoda, and when I first saw the 

 figure of Aturia Matthewsoni I had no doubt of its being an Aturia.'''' 

 — Conrad. 



Tlie above quotation embraces the whole of Conrad's original 

 diagnosis and remarks on his genus Hercoglossa, a form which clearly 

 occupies a transitional position between Nautilus proper and Aturia. 

 The first species mentioned is Nautilus orbiculatus, Tuomey,' from 

 the Cretaceous rocks of Alabama ; but since it is insufficiently defined, 

 and has not been figured, we are unable to accept it as the type of the 

 genus. Aturia Matthewsoni, Gabb,* also of Cretaceous age, is next 



1 Proc. Acad. Nat. Sci. Philadelphia, 1854, vol. vii. p. 167. 



* Geol. Survey California, Palaeontology, 1864, vol. i. p. 59, pi. xvii. fig. 31. 



