President's Address. Gl 



Loxonema (Phillips), Polyiohemoi-jsis (Portlock), and Mac- 

 Tocheilus (Phillips). By some authors these are placed in 

 the PyramidellidcG, by others in the Turbinidse,* and again 

 in the Eulimid?e.-f Be this as it may, they form a very 

 natural group in Palaeozoic rocks, with gradations one 

 between the other, uniting them together. 



Loxonema was proposed by the late Professor Phillips for 

 turriculated shells, with a sigmoidal edge to the outer lip, 

 and surface ornamented with longitudinal ridges or threads, 

 but no spiral band. :]: Nine species, met with in Scotch 

 Carboniferous rocks, have been referred to this genus, all, 

 with one exception, being found elsewhere. By many 

 writers Loxonema is considered synonymous w4th Chemnitzia 

 (D'Orbigny), but, as Professor M'Coy has observed, § its 

 species have a deeply sinuated lip and plain apex, which at 

 once separate them from those of the latter. On this subject 

 Mr Meek has made some good and terse remarks. He points 

 out II that, as originally proposed by D'Orbigny in 1839, 

 Chemnitzia is equivalent to Turhonilla (Risso, 1835). The 

 second description by D'Orbigny, in 1850, is much posterior 

 in date to that of Loxonema by Phillips, even supposing them 

 to be identical, but Meek inclines to the view that the 

 Palaeozoic shells for which Loxonema was proposed are dis- 

 tinct from those of later date, and described by D'Orbigny. 



At least two of the species met with in the Carboniferous 

 rocks of Scotland, and placed hitherto in Loxonema, are 

 spirally striated {L. polygyra, M'Coy, and L. sulcatula, M'Coy). 

 This is diametrically opposed to the original definition by 

 Phillips, and requires amendment. A genus has been pro- 

 posed by Meek and Worthen,ir Orthonema, in which the outer 

 lip is straight, and the volutions ornamented with revolving 

 carinie, but no band or slit as in MurcMsonia. I am not 

 sufficiently acquainted with the form of the aperture in the 

 above species to be able to form an opinion as to their 



* King, Mon. Perm. Foss., p. 209, qU. 



t Stoliczka, Cret. Gasterop. of India, p. 290. 



X Pal. Foss. Devon., etc., p. 98. § Brit. Pal. Foss., fas. 3, p. 302. 



II United States Geol. Survey, Territories, ix., p. 339. 



H Illinois Geol. Report, ii. , p. 380. 



