150 T, Davidson — Upper Silurian Brachiopodd. 



Maw among the debris from the old Wenlock limestone quarries at 

 Benthall Edge in Shropshire. It is not possible to determine to 

 what genus the shell should be referred, as its interior characters 

 have not been ascertained, and it was not considered right to 

 sacrifice the only specimen known in the attempt to discover the 

 character of its spiral appendages. We have therefore provisionally- 

 put it with Meristella. 



It is with much pleasure that I name this new species after its 

 indefatigable discoverer, and in remembrance of the great labour and 

 liberality with which he has assisted me in getting up the material 

 for this communication. 



7. Streptis Grayii, Dav. PL V. Fig. 13. 

 Atrypa ? Grayii, Dav., Sil. Mon. pi. xiii. figs. 14-22. 



In 1846 I picked up two or three examples of this remarkable 

 small twisted sliell at Hayhead near Walsall, and described and 

 figured it in 1848 in the Bulletin de la Soc. Geol. de France under 

 the name of Terebrahda Grayii. In 1859 Salter (in Siluria) made 

 of it a Rhynchonella. Lindstrom in 1860 a Spirigerina ? and in my 

 Silurian Monograph I provisionally put it with Atrypa^i adding, "my 

 endeavours to procure specimens showing the internal character 

 have proved fruitless, and I cannot determine exactly the genus." 

 Knowing little or nothing of its interior arrangements, I felt ex- 

 tremely puzzled and uncertain as to the genus to which the shell 

 should be referred, and, as justly remarked by Prof. James Hall at 

 p. 38 of the 16th Annual Report on the State Cabinet of Natural 

 History of New York, "so long as we remain unacquainted with the 

 interior of the shell, we are compelled to refer the species to some 

 genus having similar forms, though the fibrous or punctate struc- 

 ture may in many instances prove a valuable aid in these references." 

 I have now seen upwards of one hundred and forty specimens of this 

 remarkable species, and every individual presented exactly the same 

 exterior character, and which I have described and represented at p. 

 141 and in pi. xiii. of my Silurian Monograph. 



Possessing, thanks .to Mr. Maw's great liberality, a number of 

 good examples, I sent some of them to the Eev. Norman Glass to 

 operate upon, and after many experiments on perfectly preserved 

 specimens filled with spar and suitable to his operations he has 

 informed me that he could in none of them detect the slightest trace 

 of any calcareous support for the labial appendages — not the trace 

 of a loop or spiral skeleton, and he was of opinion that it could not 

 be referred to any of the genera into which it had been provisioiially 

 located. I therefore propose provisionally to place it under a distinct 

 genus, and have selected the name Streptis (twisted), all the specimens 

 hitherto discovered having presented that character. No calcareous 

 support for the labial appendages, cardinal process much produced, 

 hinge- teeth large and prominent. 



8. Ehynchonella ciineata, Dal. and His. PI. V. Fig. 10. 



Sil. Mon. pi. xxi. figs. 7-11. 

 Since describing this well-known species at page 164 of my 



