6B CARHONI FERGUS CEPHALOPODA OF IRELAND. 



much thicker proportions, and transversely broader whorls. Nautilus Mosqucnsis, 

 Tzwetaev' {=z sabnuh-atiis, Trautschold, non Phillips) somewhat resembles the 

 present species, but the periphery is broader and not so concave, and the sutures 

 are not so sinuous. -4. hihernicam, A. H. Foord and G. C. Crick," is closely allied 

 to A. mntabile, but differs from it in its less slender proportions, less deeply 

 channelled periidiery, and in the non-contiguous condition of the first half-whorl. 



Kemarkii. — In the 'Catalogue of F'ossil Cephalopoda, British Museum,' pt. 2, 

 1891, p. 91, A. mutabile is included in the synonymy of a species described by J. 

 Sowerby under the name of EUipsolites compressiis.^ It was afterwards discovered, 

 however, by Mr. G. C. Crick and the writer that Sowerby's species was identical 

 with the one described by that author as Ammtviite!^ llennloiri,* and it was further 

 ascertained that EUipsoUtes compressns ( = Ammonites Henslowi) was a Goniatite 

 belonging to the genus Prolecanites, Mojsisovics. This correction was published 

 with full details and illustrations of the species in the ' Geological Magazine ' for 

 January, 189-i, and subsequently in the' Cat. Foss. Ceph. British Museum,' pt. 3, 

 1897 ; this allusion to the subject will therefore be sufficient. 



Localities. — Rathfarnham, county of Dublin ; Clane and Naas, county of 

 Kildare; Cregg, near Nobber, county of ^loath ; Little Island, near Cork; Rath- 

 keale, county of Limerick 



/>. Apheleoeras Hideknioum, .-1. H. Foord ami G. G. Crick. Plate XXI, figs. 4 — 7- 



IS93. DisciTKs HiBEKNicus, J. H. Foord ond O. C. Crick. Geological Maga- 

 zine, dec. 3, vol. X, p. 251 («oodcut, p. '25-i). 



Description. — Sliell discoid, compressed; whorls three (in largest individual 

 measured), rather slowly increasing, the first half-whorl free, the rest in contact, 

 but leaving the sides of the inner whorls entirely exposed ; the impi'cssed zone 

 faintly defined on the body-chamber. The latter occupies i'uUy one-half of the 

 last whorl, and becomes free towards the aperture. Section of the wliorl subcir- 

 cular in the young, but becoming truncated-cuneiform and tetragonal in the 

 adult. Umbilicus broad and shallow, with a large central vacuity ; its walls 

 sloping in such a degree as to form a very obtuse angle with the sides of the 

 shell. Periphery convex in the free portion, concave in the last whorl, about one- 

 half of the width of the side, exclusive of the umbilical slope; bounded on each 



' • Mem. Comitc Gcol. [liussia]," vol. v, No. 3, 1S88, p. 52. 

 ' ' Geol. Mag.,' decade 3, 1S93, vol. x, p. 251 (woodcut). 



* ' Jliii. Conch.,' vol. i, IS13, p. Si, pi. xxxviii. 



* Thill., vol. iii. 1820, p. Ill, pi. cclxii. 



