DISCITOCERAS WRIGHTII. 105 



The ornamentation in tliis species is precisely similar to that of Discitoceras 

 LeveiUeanum, de Kon. 



Acuities. — This species closely resembles ViscUoceras LeveiUeanum, de Kon., 

 differing from it only in the form of the whorls, more or less I'oundcd in de 

 Koninck's species, subqnadrate in M'Coy's. 



Remarks. — I have much hesitation in regarding this species as valid. All the 

 specimens 1 have seen (all from the Cork district — Cork or Blackrock, both in the 

 county of Cork) are compressed in the dorso-ventral direction of the whorls, and 

 rendered elliptical thereby, and all but one disforteJ. M'Coy's type has been 

 lost; there is no specimen in the "Griffith Collection" (Dublin Museum of 

 Science and Art), which ought to contain it, answering to his figure (loc. cit.), 

 which shows an ornamentation, as I have said above, precisely similar to that of 

 Discitoceras LeceilJeanum. The specimen in the Griffith Collection is mainly a 

 cast showing the septa, with fragments of the test, so badly preserved as to 

 exhibit not the faintest trace of ornamentation. 



When in Brussels in 1893 I made a careful study and a drawing of the 

 specimen figured by de Koninck (' Calc. Carb.,' loc. cit.), and contained in the 

 Museum of Natural History (Pare Leopold). His specimen is distorted in a 

 similar manner to the Irish ones, thus strengthening the view to which I am now 

 strongly inclined, that B. discors represents merely distorted or compressed 

 individuals of D. LeveiUeanum. If this be actually the case, the latter species 

 would become the type of the genus, displacing the former which I proposed as 

 the type when describing the species contained in the British Museum (' Cat. 

 Foss. Ceph.,' 1891, pt. 2, p. 87). 



M'Coy was evidently not acquainted with de Koninck's species D. Levcil- 

 leannni, for he could not have overlooked its obvious similarity to I), discors, the 

 latter name suggesting the most salient feature in the ornamentation of de 

 Koninck's species, viz. the discontinuance of the ridges in the adult volutions 

 specially pointed out by M'Coy. 



Localities. — Clane, and Naas (British Museum specimen), county of Kildare; 

 Blackrock, county of Cork. 



DisciTOCEUAS WiiiGHTiJ, sp. nov. Plate XXVI, figs. 3 a — d. 



Description. — Shell discoid, rather compressed, with a somewhat planorbiform 

 configuration. Whorls about three in number, rather slowly increasing in diameter, 

 all being exposed in a shallow umbilicus with a small central vacuity. 



The whorls are somewhat flattened at the sides, the perijihery gently roundtd. 

 (Lateral pressure has altered the shape of the periphery in the specimens before 



1(5 



