166 PALEONTOLOGY OF KENTUCKY 



Platyceras multispinosum. MEEK. 



Plate XXV., figure 4. 



Platyceras multispinosum, Meek. Proc. Acad. Nat. Sci. Phil. 1871. 

 Paiyceras multispinosum, Meek. Pal of Ohio, Vol. 1, page 210 1873. 



Shell attaining a large size, considerably larger than its near relative, the P. 

 dumosum ; it has a very thin shell, is depressed sub-ovate and very oblique. 

 Its apex is free in the casts may not be so in the perfect shell ; comparatively 

 stout, and obliquely coiled for about one and one-half volution ; after this the 

 body-whorl expands very rapidly to the aperture, occupying in this part of 

 the shell less than half a volution. 



Aperture very large and nearly round ; lip entire ; neither sinus nor undu- 

 lated. 



Surface without any surface-markings except the numerous closely arranged, 

 slender, tubular spines on well preserved shells, or their small, depressed, 

 smooth, undefined tubercles or nodules on the internal casts. In regard to 

 general size, and the proportion of its different dimensions, this shell differs 

 greatly. The illustration, figure 4, on plate 25, shows a large-sized specimen. 

 This species differs from Platyceras dumosum by its considerably larger size, 

 its more oblique, depressed and more rapidly expanding form, and mainly by 

 its more numerous and more slender spines. Specimens belonging to this 

 species will be very seldom confounded with P. dumosum ; their difference 

 is noticed at the first glance, whether they are shells or internal casts. The 

 spines are seldom attached to the specimens ; they become separated by exfoli- 

 ation, but are often preserved in the matrix. 



Formation and Locality- Occurs in the Corniferous limestone of the Devonian formation at the 

 Falls of the Ohio, and in other places in Jefferson county, Ky., and Clark county, Ind. It is not rare, 

 though fair specimens are not abundant. 



Platyceras rictum. HALL. 



Platyceras rictum, Hall. Desc. New Sp. of Poss , p. 7 1861. 



Platyceras rictum, Hall. 15th Regent's Rep., p. 35 1862. 



Platyceras rictum, Hall. Illust. of Dev. Fossils, pi. 4 1876. 



Platyceras rictum, Hall. Pal. N. Y., Vol. 5, pt. 2, p. 131885. 



Shell very depressed, arcuate or sometimes obliquely sub-conical; width 

 equalling and often exceeding height. Apex or nucleus minute, the spire 

 enrolled for about one turn and a half, when it abruptly expands, spreading 

 more upon the right posterior side, and becoming greatly extended and ex- 

 panded in front. 



The dorsal line of the first volution is continued in an oblique angular ridge, 



