Yol. 68.] LOWER CARBONIFEHOirS GASTEEOPODA. 305 



PiTHODEA AMPLissiMA De Kon. (PI. XXX, figs. 1-3.) 



PitJwdea ampUssima L. G. De Koninck, 1881, ' Faune Calc. Carb. Belg.' pt. iii, 

 Ann. Mus. Roy. Hist. Nat. Belg. vol. vi, p. 88 & pi. viii, figs. 1-3. 



Diagnosis. — Shell composed of more than six whorls. There is 

 a flat band bordered by raised threads, situated below the middle 

 of the penultimate whorl, and above the middle of the body-whorl. 

 Fine lines of growth curve slightly backwards to this band, form 

 indistinct crescents on it, and then pass downwards almost ver- 

 tically. The ornamenting spiral threads are irregular in strength, 

 fine threads being sometimes intercalated between strong ones. 

 Columellar lip nearly straight. 



Remarks and resemblances. — Portions of two shells in the 

 collection of Mr. Joseph Wright, Belfast, appear conspecific with 

 De Koninck's Fithodea amplissima. Neither of them has attained 

 the proportions of his largest specimen, but one must have been 

 of about the same size as the smallest shell which he figured in 

 pi. viii, fig. 3. A new drawing from the original is here reproduced 

 for comparison (PI. XXX, fig. 3). 



, Dimensions. — The largest fragment (PI. XXX, fig. 1) consists 

 of parts of two whorls which measure 4*7 centimetres in length, 

 the width of the penultimate whorl= about 3*2 cm. The other 

 specimen (fig. 2) has four broken whorls in a length of 3'9 cm. 



Locality and horizon. — Cork; Lower Carboniferous Lime- 

 stone (Etage de Yise, Assise vi). 



PiTHODEA PEKCINCTA (Portlock). (PI. XXX, fig. 4.) 



Ilacrocheilus percinctus J. E. Portlock, 1843, ' Report on the Geology of 

 Londonderry, &c.' p. 419 & pi. xxxi, fig. 10. 



This shell greatly resembles P. amplissima De Kon. It differs 

 in the band not being so distinctly defined, and in the ornamenting 

 threads being more nearly equal in strength. De Koninck noticed 

 the resemblance, but evidently had merely seen the figure and not 

 the actual specimen : therefore, owing to the band not being repre- 

 sented, he considered that the shells belonged to different genera. 

 They are certainly congeneric and possibly conspecific, but since 

 only one worn example of Portlock's species is known to me it is 

 impossible to decide as to the value attaching to the differences. 

 It is thus advisable to retain both names for the present, although 

 the acquisition of more specimens may make it necessary for De 

 Koninck's specific name to give way to that of Portlock. 



Dimensions. — The holotype is the specimen described by 

 Portlock, which is in the Museum of Practical Geology, London. 

 It is imperfect, and the three existing whorls = 8*7 centimetres in 

 length and about 5 '4 cm. in width ; the latter dimension would 

 probably have been greater if the shell had been entire. 



Locality and horizon. — Derryloran (Tyrone). Lower Carbo- 

 niferous Limestone. 



