198 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



narrower and more numerous whorls and conspicuous sj)ival strise, the latter beina; 

 entirely absent in (t. nrciimnodosiini. 



None of the species here compared with (t. nrnunrimhiKnm have been fo\md up to 

 the present time in Ireland. 



In his important paper on the " Marine Fossils from the Coal Measures of 

 Arkansas," ' J. Perrin Smith figures a specimen of Gastriocerns to which he does 

 not assign any name, biit which he describes as closely resembling G. Marin nnm, 

 de Verueuil, in its young stage; while it is distinguished from G. Mnrinuum in its 

 adult stage by its narrower and more highly arched whorls. It appears to me that 

 this species is intermediate in character, when mature, between G. Luteri and 

 G. Miiriarnim, and thus suggests affinities with G. circumnoflosum, especially in the 

 character of its ornaments, which consist of strong tubercles on the sides of the 

 whorl ; " which on the young stages are like those of G. Marianum, but on the adiilt 

 form ribs reaching halfway from the umlnlical shoulders to the ventral [peripheral] 

 portion of the shell." 



Mr. Perrin Smith describes G. Marianum. in the same paper, giving figures of it 

 in several stages of growth, up to a diameter of 54 mm. He recognises also in 

 the same beds other " European Coal Measure forms not before known in 

 America," "snz. Gnnoranliina aJ'ifnrme, J. Sowerby, and I'rrmnrifc.'^ cychilohus, J. 

 Phillips. 



Bemarl's. — In the al)sence of the suture-line the generic position of the present 

 species has been determined in conformity "nnth its close resemblance to well-known 

 species of Gastriocras, especially to G. Listi'vi, its affinities with which have just 

 been pointed out. 



The specimens upon which the present description is based are a series of empty 

 moulds crowded together upon the surface of a fragment of carl)onaceous shale. 

 The weathering to which the rock has been subjected, though considerable, has not 

 been so severe as to obliterate the coarser ornaments of the shells which originally 

 occupied the moiilds. Of these ornaments very distinct remains are imprinted 

 upon the concave surfaces of nearly all the moulds. By filling the latter Avith 

 plaster of Paris, and thus producing a cast of the siuface of the slab, the form of 

 the original shell was rej^roduced, the figures 10 and 11 on PI. XLIX representing 

 two of the best preserved surfaces. The shells vary in size from 2 mm. (some 

 probal)ly even smaller) to ;51 mm., the diameter of the larger of the two specimens 

 figured. 



For the cast, which was made in the Dublin Museum of Science and Art, I am 

 indebted to the kindness of Mr. G. H. Carpenter of that museum. I was much 

 assisted further in the determination of the present species by Dr. Arthur Smith 

 Woodward, F.R.S., who very kindly had casts made for me in tlK> British Museum 



' ' Proc. American Phil. Soc, Philadelphia,' vol. xxxv, Nov., 180G, No. l.l-i, \\. 202, jil. xx, fig. 1. 



