BRITISH SILURIAN BRACHIOPODA. 139 



In external shape this small species bears much general resemblance to KonincJcina 

 Leonliardi (Wissmann) ; and, if it is provided with spiral appendages, they may possibly be 

 somewhat similarly arranged. Anyhow, thanks to Mrs. R Gray's discovery of several 

 perfect internal casts of the ventral valve, and of a specimen of the same valve with its interior 

 well preserved, it has been possible to define some of its characters, which are exactly 

 similar to those of the specimen from Cerrig-y-Druidion in Wales. The valve is possessed 

 of a kind of shoe-lifter process, somewhat similar to what we find in Merista or Camarium 

 of Hall. Unfortunately we know nothing with respect to the interior of the concave or 

 dorsal valve. The fossil does not appear to be very rare at Drnmmuck, so that it is to 

 be hoped that better examples will be collected, and thus to clear up the uncertainty as to 

 the genus to which the species should be referred. See also p. 134. 



Genus — Streptis, Bav.^ 1881. 



22. Streptis Grayii (Atrtpa ?), Dav. Sil. Mon., PI. XIII, figs. 14—22. 



Streptis Gkayi, Dav. Geol. Mag., new ser., vol. viii, p. 150, pi. v, fig. 13, 1881. 



The exterior characters of this puzzling little shell have been fully described and 

 illustrated in p. 141 of my 'Silurian Monograph ;' but I have never been able to feel 

 satisfied with respect to its internal characters, so as to determine whether the shell was 

 provided with calcareous lamellae for the support of the labial appendages. 



In 1846 I picked up two or three examples at Hayhead, near Walsall, and described 

 and figured the fossil in 1848 under the name of Terebratula Grayi. In 1859 Salter (in 

 ' Siluria ') made of it a Bliynchonella ; Lindstrom, in 1860, a Spiriyerina ? ; and in my 

 ' Silurian Monograph ' I provisionally put it with Atrypa ?, adding " My endeavours to 

 procure specimens showing the internal characters have proved fruitless, and I cannot 

 determine exactly the genus." As justly remarked by Prof. Hall, at p. 38 of ' The 16th 

 Annual Report of 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 structure may, in many 

 instances, prove a valuable aid in these references." 



Possessing, thanks to Mr. G. Maw's liberality, a number of good examples, 1 seut 

 some of them to the Rev. N. Glass to operate upon, and after many experiments on 

 perfectly preserved specimens, filled with spar and suitable to his operations, he informed 

 me that he could in none of them detect the slightest trace of calcified supports, nor 

 the trace of a loop or spiral, and he was of opinion that it could not be referred to any 

 of the genera into which it had been provisionally located. I therefore, in 1881, proposed 

 to place the fossil under a distinct genus, and selected the name Streptis (twisted), all the 



