378 GENERAL SUMMARY TO 



numerous thread-like, radiating, rounded striae, which here and there augment in thick- 

 ness and prominence, producing small, hollow, adpressed spines, similar to those observ- 

 able in 0. resupinata, 0. Keyserlingi, and 0. Morganiana. 



None of the authors who have described the Enteletes Lamarckii seem to have been 

 acquainted with the interior of its valves. I was, however, fortunate enough to procure 

 a specimen from the Carboniferous Limestone of Mjatschkowa near Moscow, and after 

 some patient labour was able to remove the hard white limestone that filled its interior 

 so as to show its internal characters. 



In the interior of the ventral valve a strong tooth is situated on either side of the 

 base of the fissure, and from this converging prominent dental plates extend along the 

 bottom of the valve to a little less than half its length. In the hollow between these 

 plates or septa commences to rise a large, prominent, mesial plate, which becomes most 

 elevated towards its anterior extremity. In the interior of the dorsal valve there exist 

 two small curved lamellae, somewhat similar to what we find in Rhynchonella, and to 

 these in all probability were attached the spirally-coiled, fleshy labial appendages. 

 Under the socket-pits and on each side two slightly deviating septa partly surround and 

 enclose the muscular scars, and they are longitudinally divided along the middle by a 

 narrow ridge. 



These characters, in an allied species, the Enteletes latesinuatus, Waagen, have been 

 well displayed and illustrated by Dr. Waagen in pi. 57, figs. 5 and 6 of the third part of 

 his ' Salt-Range Brachiopoda.' 



The so-termed genus Syntrielasma of Meek, 1872, is a synonym of Enteletes. In 

 1850 Prof. W. King proposed a genus Schizophoria to include such species as the 

 Orthis (Jnomia) resupinata of Martin ; whether we should be justified in retaining 

 this genus or of including it in the Enteletes group is a question still to be determined. 

 The Orthis Morganiana of Derby seems to be intermediate in character between Enteletes 

 Lamarckii, and Schizophoria resupinata, thus denoting the close relationship between 

 the so-termed genera. 



The genus Skenidium, Hall, seems to be well distinguished from Orthis, Enteletes, and 

 Schizophoria, and is described at p. 48 of my ' Devonian Supplement.' 



It is more difficult to deal in a satisfactory manner with the many genera that 

 have been included in the family Strop homenida ; all of them are distinguished from the 

 Orthisida by having their triangular fissure arched over by a pseudo-deltidium. 



1. Orthisina, d'Orb, 1847, type 0. anomala, seems to be a well-characterised genus 

 on account of its interior arrangements, which I fully described and illustrated in 

 the ' Geologist ' for March, 1859, as well as at p. 29 of my ' Permian Monograph.' 

 It has been suggested that the generic name Klitamboniles, Pander, 1830, should hold 

 priority over that of Orthisina ; but, as Pander gives several generic names to species 

 presenting the same characters, 1 prefer retaining d'Orbigny's name, which moreover 

 is now in general use. 



