LINGULA. 205 



this controversed question, my object having been attained if I have been able to lay 

 before the geological and palacontological reader the views of two such eminently dis- 

 tinguished anatomists as Mr. Hancock and Dr. Gratiolet, and no doubt time will prove 

 which is the correct interpretation ; for now that the question at issue has been made 

 known, it will not be difficult for some observer who may happen to be where Lingula 

 is found alive to notice whether or not the valves do slide upon one another. We will 

 now conclude the little we had deemed necessary to say of the animal by observing that 

 the so-termed oral arms are not supported, as in many of the articulated genera, by a more 

 or less complicated system of lamellae ; that they are fleshy, with their spires directed 

 towards each other. 



After much examination 1 have reduced the so-termed species of British Carboniferous 

 Lingulse to four, viz., L. squamiformis, L. myiiloides, L. Crcdneri (which may possibly 

 be a variety of L. mytiloides), and L. Scotica. 



LlNGULA SQUAMIFORMIS, Phillips. PI. XL1X, figS. 1 10. 



IiiNGULA squamiformis, Phillips. Geol. of Yorkshire, vol. ii, pi. ix, fig. 14, 1836. 



— — Portlock. Report on the Geol. of Londonderry, &c, pi. xxxii, 



fig. 5, 1843. 



— M'Coy. British Pal. Foss., p. 475, 1855. 



— — Dav. Mon. of Scottish Carb. Brach., pi. xi, fig. 14, 1861. 



Spec. Char. Shell longitudinally oblong, one third or less longer than wide, with 

 sub-parallel sides, the broadest towards the anterior extremity, the frontal margin 

 assuming either a very slight inward or outward curve. The anterior portion is gradually 

 curved on either side, the beak being rounded or but slightly angular at its extremity in 

 the dorsal valve, with a thickened margin, tapering, pointed retrally at its termination in 

 the ventral one, which is consequently so much longer than the opposite valve. The 

 valves are slightly convex, but somewhat depressed along their middle. In the dorsal one 

 there exists a small apex close to the rounded margin of the beak, and from which usually 

 radiate three small, rounded ridges, separated by shallow sulci. The external surface in 

 both valves is covered with numerous fine, concentric stria?, or lines of growth, giving to 

 the shell a beautifully and delicately sculptured appearance, for the minute plications of 

 growth succeed each other with much regularity, while some stronger lines or interruptions 

 of growth are produced at variable distances. The internal muscular impressions are 

 similar to those already described, the occlusor and external adjustors of Hancock being 

 especially observable. Dimensions variable ; two British examples have measured — 



Length 19, width 13 lines. 



>i *» »» u 2 >> 



Obs. This is a common species in certain Scottish strata and localities, and is found 

 likewise in England and in Ireland, and can be distinguished from its congeners by shape 



