GLYPHIOCERAS (MUENSTEROCERAS) ELLIPSOIDALE. 195 



sevenths of the same. Number of whorls not known ; inclusion about two-thirds. 

 Umbilicus deep, with steep, nearly vertical sides and subangular margin, exposing 1 lie 

 edges of the inner whorls, about two-sevenths of the diameter of the shell in width. 

 "Whorl very distinctly semi-elliptical in cross-section, height about three-fourths of 

 the width ; indented to nearly one-third of its height by the preceding whorl. 

 Sides slightly covex, somewhat flattened near the umbilicus ; umbilical zone narrow, 

 slightly concave, nearly perpendicular to the plane of symmetry of the shell. Body- 

 chamber occupying the whole of the last whorl ; peristome with a widely curved 

 lateral crest and broad and deep hyponomic sinus. Test smooth, with faint lines of 

 growth near the aperture. 



Dimensions. 



Type specimen from Kildare, in the 



Museum of Science and Art, 



Dublin. 



Diameter of shell .... 83 # mm. 



,, umbilicus (edge to edge) . . 23*5 ,, 



„ ,, (suture to suture) . . 2O0 ,, 



Height of outer whorl . . . 3(3 # ,, 



,, above preceding whorl . . . 25*0 ,, 



Thickness at umbilical margin . . . 47*0 „ 



Affinities.— The only species which resembles the present one in any marked 

 degree is that which I have called G. (M.) obesum, which, being figured upon the 

 same plate, can be readily compared. The form of the shell in each is considerably 

 inflated, and in both the peripheral lobe of the suture-line has the subparallel sides 

 characteristic of Muensteroceras. The test in both is smooth. In cross-section, 

 however, the whorl in G. (M.) ellipsoidale is broadly arched above ; in G. obesum it 

 is narrower as well as being distinctly flattened — at least in the region of the 

 body-chamber. 



There is not very much difference between them in their umbilical characters. 

 Allowing for the distortion in the specimen representing G. (M.) obesum, the 

 umbilicus in this species is relatively smaller than that of G. (M.) ellipsoidale. Its 

 more inflated and smooth shell and larger umbilicus suffice to distinguish the present 

 species from G. striatum, J. Sow. 



Remarks. — Mr. Crick 1 refers a specimen in the British Museum (No. C. 294) to 

 the present species, but with some doubt ; it is from the Carboniferous Limestone 

 of Rathkeale. 



Localities. — Kildare (exact locality in the county unknown); Little Island, near 

 Cork ; (?) Rathkeale, county of Limerick. 



1 Loc. cit., p. 450. 



29 



