﻿BEITISH FOSSIL CEPHALOPODA. 213 



that should make it a Lituites ; nor is there any sign of asymmetry that should 

 place it in Trochoceras. 



Distribution. — In the Wenlock Shale, Usk (3), Dudley (1), and in the Wenlock 

 Limestone of Ledbury (1) and Dudley (3) ; in the Lower Ludlow, Ledbury (2) ; 

 also in the Upper Ludlow, Presteign ? 



Subgenus Trocholites. 

 Nautilus (Trocholites) anguiformis, Salter, PL XXVIII. figs. 2, 2a. 



1855. Lituites anguiformis, Salter in Appendix to ' Palaeozoic Fossils,' pi. 1l, fig. 26, p. viii. 

 1855. Trocholites anguiformis, M'Coy, ' Pal. Foss.' p. 323. 



Type. — Rate of increase 1.46. Last whorl .29. Thus the whorls are scarcely in 

 contact according to this measure, but the shell having gone they may have touched 

 when it was present. The specimen is also somewhat compressed. The section is 

 elliptic, with the long diameter in the plane of curvature, i.e. the whorl-breadth is 

 greater than the thickness. About 3 whorls are seen, and there was possibly an 

 initial vacuity. No ornaments beyond very feeble lines of growth. There are no 

 signs of any change of shape or curvature in the body-chamber. The septa make 

 a curve which is concave forwards on the side, and another shallower on the 

 front, with a low convex curve between. In the inner whorls they are r? the whorl- 

 breadth apart, and have the curves less marked, but they become closer, up to f 

 the whorl- breadth, at last. The septal surface has considerable convexity. The 

 siph uncle is internal, of small size, on a prominence of the septal surface, as seen 

 from behind. From the Bala Limestone, Llangollen. In the Woodwardian Museum. 



General Description and Relations. — No other example has been seen. 



Nautilus (Trocholites) planorbiformis, Conrad, PI. XXIX. figs. 8, 8a, 9, 9a. 



1847. Trocholites planorbiformis, Conrad, ' Journ. Acad. Nat. Sc. Philadelphia,' vol. viii. p. 274,. 



pi. 17, fig. 1. 



1848. „ „ HaU, 'Pal. New York,' vol. i. p. 310, pi. 84, fig. 3. 

 1852. „ „ M'Coy, ' Palaeozoic Fossils,' p. 324. 



' 1852. „ „ Salter, Appendix A to ' Palaeozoic Fossils,' p. 8; 



1866. Lituites planorbiformis, Salter, 'Mem. Geol. Surv.,' vol. iii. p. 358, pi. 25, fig. 5. 



1873. „ „ Salter, ' Cambrian and Silurian Fossils,' p. 71. 



Syn. 1845. Nautilus prim.zevus, Salter in Sedgwick, ' Quart. Journ. Geol. Soc.' vol. i. p. 20 (name only). 



1852. Lituites Hibernious, Salter, 'Brit. Assoc. Eep.' p. 61. 



Type. — The example figured by Hall shows a rate of increase of about 1.4, and 

 the last whorl .34, but the figure is variable in this respect. There is no want of 



