SOLENOCHEILUS ? HIBERNICUS. 129 



The section is broadly sagittate, the periphery constituting the apex of the 

 triangle. 



The body-chamber is large, extending to about three-fourths of the circum- 

 ference of the last whorl. The periphery is rather narrowly rounded, and merges 

 in the sides as they gradually expand towards the edge of the umbilicus. The 

 aperture is not preserved in any of the specimens that have come under my notice. 

 The apex, so far as it can be observed, is obtusely pointed as in other shells 

 belonging to this genus. 



The septa, as indicated by the sutures, are somewhat widely separated. In a 

 specimen contained in the " Gilbertson Collection " at the British Museum (No. 

 C. 212), from Bolland, Yorkshire (PI. XXXVI, fig. 2), the sutures increase from 

 a distance of 10 mm. to one of 20 mm. apart where the diameter of the shell is 

 7G mm. The siphuncle is not known, but it is assumed to be peripheral, hence the 

 reference of the species to Solcnocheilus. The surface of the shell is perfectly 

 smooth. 



Dimensions. 



Type specimen in the Specimen in Britisii Museum 

 British Museum (" Gilbertson Collection," 



(No. C. 4505). No. C. 212). 



Diameter of shell (about) . .117 mm. . 91 "5 mm. 



„ umbilicus (edge to edge) . 24 „ . 17 ,, 



„ ,, (suture to suture) . 18 ,, . — ,, 



Height of whorl (dorso-ventral) about . 67 „ . — „ 



Thickness at umbilical margin . . 82*5 „ . 85 ,, 



Affi,n{ties. — The angularity of the umbilical margin distmguishes this species 

 from Sulenocheihis dorsalis, which it resembles in its general form and septation ; 

 and this seems to justify its reference to Solenocheilus, though the siphuncle is 

 unknown. S. ntlantoideus, de Koninck,^ though possessing a similarly angulated 

 umbilical margin, has a very different form in cross-section, caused by its more 

 broadly rounded periphery, while it has also at least one whorl more than 

 S. liiberniciis, giving the umbilicus a much greater width. 



Remavlcs. — This species is represented in the Dublin Museum of Hcience and 

 Art Ijy a recently acquired specimen from Little Island, near Cork. Like many of 

 the Carboniferous Limestone fossils from this part of the south of Ireland, it is 

 greatly distorted, the peripheral area being completely flattened in the region of 

 the body-chamber in the dorso-ventral direction, causing the sides of the shell to 

 be much narrowed and the periphery proportionately widened. The flattening 

 and distortion has also affected the septate part of the shell, Avhich is squeezed into 

 an elliptical form. The angular edge of the umbilicus is marked l)y a narrow rim, 



1 "Faune Cak. Carb. Belg.," 1878 ('Auu. Mus. Roy. d'Hist. Nat. Belg.,' torn, ii), pt i, p. 97, 

 pi. xi, figs. 1, 2. 



