VEST! NAUTILUS IMULTICARINATUS. 93 



Vestinautilus mui-ticaeinat[is, /. de G. Soiverhi/, sp. Plate XXV, figs. 4 a, h, 5. 



1825. Nautilus multicarikatus, J. de C. Soiuerhy. Miu. Conch., vol. v, p. 120, 



pi. cceclxxxii, fig. 1 (excl. fig. 2). 

 1836. — —J. Phillips. Geology of Yorkshire, pt. 2> 



p. 232. 



1843. — — /. E. Portloch. Geology of Londonderry, 



p. 405. 



1844. — (Temnocheilus) porcatus, F. M'Coy. Synop. Cai-b. Fos?. 



Ireland, p. 22, pi. iii, fig. 6. 

 1800. Temnocheilus multicarinatus, R. Qriffitli. Journ. Greol. Soc. Dublin, 



vol. ix, p. 57. 

 1878. Nautilus multicarinatus, L. G. de KonincTc. Faune Calc. Carb. 



Belgique (Ann. Mus. Eoy. d'Hist. Nat. 

 Belgique, Paleont., torn, ii), pt. 1, p. 121, 

 pi. XXV, figs. 2 a — c. 

 1891. CcELONAUTiLUS MULTICARINATUS, A. H. Foord. Cat. Foss. Ceph. British 



Museum, pt. 2, p. 114, fig. 16. 

 18!)3. Vestinautilus multicarinatus, A. Hyatt. Carboniferous Cephalopods. 



Second paper. Geological Survey of 

 Texas, Fourth Annual Eeport, 1892, 

 p. 420. 



Description. — Shell thick-discoid, composed of two and a half or three 

 volutions, the sides of which are completely exposed in a deep, funnel-shaped 

 umbilicus having a small, central vacuity. The whorls increase rapidly in 

 diameter, the peripheral area projecting laterally and thereby greatly overhanging 

 the dorsal or antiperipheral area. The zone of impression is distinct, its 

 boundaries being those of the periphery. The section is subhexagonal in outline, 

 the sides being represented by a very narrow zone bounded by strong keels. 

 The periphery is broadly and tolerably evenly rounded, and is divided in all stages 

 of growth into two distinct elevations by a narrow, median furrow ; these 

 elevations are highest on each side of and near to the furrow, from whence they 

 slope abruptly down to the umbilical margin. Here the narrow zone, referred to 

 above, occurs, and from this the steep declivities of the umbilicus, slightly inflated 

 in their lower third, fall to the edge of the suture of the shell. It is to be 

 observed that the lateral or narrow zone, as I have called it, is proportionately 

 wider in the young and adolescent stages {i. e. in individuals measuring respec- 

 tively 20 mm. and 45 mm. in diameter) than in the adult (?) shell (75 mm. in 

 diameter).^ 



' It is not absolutely certain that the individuals of this species known up to the pres'ent time 

 are in the adult stage of their growth, or that there may not be found much larger individuals than 



