4r4:4: Mr. G. C. Crick on some 



feeble somewhat inequidistant rib?!, which, arising at the 

 umbilical margin, pass thence obliquely backward as far as 

 the margin of the periphery, whore they bend somewhat 

 abruptly backward, and form on the periphery a deep and 

 wide hyponomic sinus; on the periphery the ribs become 

 nearly equidistant, fairly coarse, and separated by interspaces 

 of about their own width ; the ornaments gradually disappear 

 on the outer whorl, those on the lateral area disa])pearing 

 first, and the ribs on the periphery at about the middle of the 

 last whorl. The whole surface of the test with very tine 

 growth-lines. 



Dimensions, 



Diameter of shell 113-5 mm.* (100) 



Widtli of umbilicus (at suture of shell) 3:? „ (23-0) 



Width of umbilicus (at its margin) . . 40 „ (35-2) 



Heioht of outer whorl 43-5 „ (38-3) 



Ditto above preceding whorl about 35 „ (30'8) 



Thickness of outer whorl 44 „ (38-7) 



Remarks. I have seen only two examples of the present 

 species ; they are both in the collection of Dr. A. H. Foord, 

 of Dublin. The larger of these is fairly well preserved and 

 is regarded as the type specimen (see fig. 8 a, h). The smaller 

 example has a very imperfect and somewhat distorted outer 

 whorl, but exhibits the sculpture of the shell at a diameter of 

 about 62 millim., and shows that the ribbing becomes obso- 

 lete on the body-chamber at a diameter of about 94 millim. 

 I have been able to display the suture-line in this specimen 

 where the diameter is about 51 millim., i. e. where the radius 

 of the shell is about 29 millim. (see fig. 9). 



Affinities and Differences. Of the Irish Goniatites that are 

 known to me the sculpture of the present species (up to a 

 diameter of about 10 millim.) closely resembles that of 

 De Koninck's Goniatites plicatilis + ; but that is a very much 

 more inflated shell, and the umbilical zone of its outer whorl 

 is wider and more sloping than that of the present species. 

 This species appears to bo also related to Perici/clus clanensis J, 



* This sp(;cimen has been broken across and tlie fissure (illed with 

 calcite, so that the diameter of the shell aud the heiglit of the last whorl 

 appear to be greater than they really are ; the diameter appears to be 

 122 millim. and the height of the outer whorl 55'o millim. 



t L. G. de Koniuck, " Sur qnelques C^phalopodes nouveaux du Calcaire 

 carbonifere de ITrlande,'' Ann. 8oc. geol. de Belg. vol. ix., McSmoiros, 

 p. 55, pi. V. figs. 3 &: 4 (erroneously stated to be pi. vi. figs. 3 & 4). See 

 supra, p. 441. 



I See siq>ra, p. 43G, 



