STROBOCERAS SULCATUM 63 



" The reader will find it convenieat to number the plates consecutively in manuscript according 

 to the following corrections, as the references in the text very generally disagree with the numbers 

 and contents of the plates in consequence of an oversight by'which a provisional nomenclature was 

 accidentally retained in printing the plates, the text having been subsequently written." 



Now it would appear that de Koiiinck never saw this " note." for he writes 

 under his description of " NaiitHtis blsulrafus" (' Calc. Carb.,' i, p. 128) tliat in 

 the first copies of M'Coy's work that were distributed the syllable hi- prefixed to 

 siilcatns in the plates had been erased, leaving only the latter name ; and accounts 

 for this verbal alteration by saying it was probable that during the printing of the 

 diagnosis of the species M'Coyhad changed his mind as to their names, which was 

 no doubt the case, but did not, I think, justify de Koninck in adopting a name 

 " blsulcatus," a name which, as described in the " note" above quoted, belonged to 

 a " provisional nontienclature," appearing only in the list of names appended to the 

 plate whereon the species was figured. I regard M'Coy's figure' as essentially 

 agreeing with " Nautilus" sulcatus, with which I unhesitatingly associate it, Irish 

 specimens that have come under my notice upholding me in this conclusion. I 

 have one now before me from Little Island, Cork, which is the only locality for it 

 given in Griffith's " Localities of Irish Carb. Fossils," arranged as an appendix 

 to the ' Synopsis ' (p. 228). 



I will take the opportunity here of correcting the synonymy of S. bisnhafus, 

 de Kon., sp. {Discites bisulcatus), in the 'Cat. Foss. Ceph. Brit. Mus.,' pt. 2, 

 p. 96, by deleting, in conformity with the foregoing observations, the references 

 dated 1844 and 1855. I would also call the attention of the reader to my 

 " remarks " in the work just quoted. 



The Belgian species differs from Sowerby's (in which I include the one 

 described and figured by M'Coy) in its more compressed form, as demonstrated 

 in the following table of measurements, in which it will be seen that the height of 

 the outer whorl is much greater in proportion to the thickness in the specimen 

 from Vise than in those from Cork, Ireland, and Castleton (?), England. 



Dimensions. 



Sowei'b.v's t\\w, 

 Brit. Mus. (yonnir). Little Isl., Cork. Vise, Belg. 



Diameter (approximate) of shell . . 25-5 mm. 41 mm. 42 mm. 



„ „ umbilicus (from 



edge to edge) . ? 22 „ ? 



,, ,, umbilicus (from 



suture to suture 

 Height of outer whorl (dorso-ventral) 

 Thickness of outer whorl 



1 It is unfortunately the case that many of the specimens figured in the ' Synopsis' have been 

 lost and amongst them the original of this figure. 



