new or little-known Goniatites from Ireland. 



433 



defined ; sides feebly convex, a little flattened near the 

 umbilicus, and becoming more flattened and convergent on 

 the body-chamber; umbilical zone well defined, narrow, 

 almost perpendicular to the plane of symmetry of the shell. 

 Body-chamber occupying nearly a complete whorl ; aperture 

 not seen, but the peristome (judging by the lines of growth) 

 probably with a broad feeble lateral crest and a fairly deep 



Fio-. 2. 



Perici/clus trapezoiduhs.- -Lateral view of the type specimen, showing 

 the ornaments of the shell, as well as some ot' the septa of the earlier 

 portion of the outer whorl. Carboniferous Limestone : St. Doulagh's, 

 Co. Dublin, Ireland. Drawn from an example in the collection of 

 Dr. A. H. Foord, F.G.S. About three fifths natural size. 



hyponomic sinus. Depth of chambers not seen ; suture-line 

 only imperfectly seen. Test ornamented with narrow promi- 

 nent ribs, which pass obliquely backward from the umbilical 

 margin, cross the lateral area in a feeble anteriorly convex 

 curve, and form on the periphery a fairly deep and wide 

 (hyponomic) sinus ; interspaces flat, nearly twice as wide as 

 the ribs ; the whole surface of the ribs and interspaces (when 

 well preserved) with fine close-set lines of growth, especially 

 on the body-chamber. The outer whorl with numerous (nine 

 or ten) constrictions, following the course of the ornaments 



