PERICYCLUS MULTICOSTATUS. 139 



the rib immediately posterior to each of the latter being somewhat stronger than 

 the rest ; bifurcation takes place here. 



Dimensions. 



British Museum (C. 5934). 

 Inflated form. Compressed form. 



Diameter of shell 



,, uml)ilicus 



. 40 mm. 



. 10 „ 



. 16 „ 

 preceding 



. 12 „ 



Thickness at umbilical margin . 24*5 ,, 



Height of outer whorl 



„ 5, above 



whorl 



'b' 



45 



mm 



11-5 



>i 



20 



» 



15 



j> 



25 



j> 



Affinities. — The affinities between this species and P. multicostatus are pointed 

 out under the description of the latter. It is also nearly related to P. Kochiy 

 Holzapfel/ but is more widely umbilicated and more compressed. The fineness of 

 its ribbing, added to the periodic constrictions, brings it also into relationship with 

 " Goniatltes" {Perici/clus ?) impressus, de Kon., sp.^ This comparison applies 

 especially to the compressed form of P. Doohylensis ; another species related to 

 the last named is "Goniatites" (P- .^) virgatus, de Kon., sp.,^ which is, however, 

 still more compressed, and has a smaller umbilicus. 



BemarJcs. — This species is apparently greatly restricted in its stratigraphical 

 range in the horizontal sense, being confined, so far as is known, to the two 

 localities cited below. It was collected at Doohyle by the writer in a small slab of 

 decomposing limestone, in a railway cutting on the line of the Limerick and 

 Foynes Railway, not far from Rathkeale. The type specimen is in the British 

 Museum, but others are to be found in the Dublin Museum of Science and Art. 



Localifij. — Doohyle, near Rathkeale, and Glenbane (compressed form), county 

 of Limerick. 



Per[cyclus multicostatus, sp. nov. Plate XXXVII, figs. 7 a — c. 



Description. — Shell discoidal (rendered elliptical by rock pressure), inflated, 

 rather narrowly umbilicated, greatest thickness at the umbilical margin, where the 

 shell expands slightly near the aperture ; height of outer Avhorl, compared witb 

 this dimension, as 5 : 7. Wliorls few, inclusion fully three-fourths. Umbilicus 



^ 'Paliiont, Abhandl.,' Dames unci Kayser, vol. v, i, 1889, p. 35, pi. iii, figs. 2 — 7. 

 2 "Faune Calc. Carb. Belg.," 1880 ('Ann. Mus. Eoy. d'Hist. Nat. Belg.,' torn, ii), pt. ii, p. 118, 

 pi. xlix, fig. 3. 



^ Loc. cit., p. 118, pi. xlix, fig. 4. 



