Yol. 67.] FROM THE PAEADOXIDES BEDS OF COMLEY. 303 



on the Shoot-Hough Road, Comley, in a band of the Shoot-Rough- 

 Road Elags, associated with Billingsella lindstrcemi, var. salopiensis. 



Acrotreta aff. sociALis von Seebach. (PL XXYI, figs. 11 a-llb, 

 12, & 13^136 [Tn 



1865. Acrotreta socialis von Seebach, Zeitschr. Dentsch. Geol. Gesellsclu 



vol. xvii, p. 341 & pi. viii a, figs. 1-4. 

 1903. Acrotreta socialis and cf. A. schmalensei Walcott, Proc. U. S. Nat. Mus. 



No. 1299, vol. xxv, pp. 699 & 597. 



Numerous specimens of a small Acrotreta have been obtained 

 from the Shoot-Rough-Road Flags. The typical form has the 

 pedicle-valve moderately elevated ; the apex (bearing a minute 

 foramen) excentric, but not overhanging the hinge-line ; the false 

 area well-defined, and showing a distinct pedicle-furrow. The 

 surface is marked by growth-ridges, which in some specimens are 

 rugose. The interior shows an apical callosity of moderate size 

 with the foraminal tube well displayed. The brachial valve is 

 slightly convex, and bears internally a strong median ridge and well- 

 marked cardinal scars, with occasional traces of other scars. 



This form agrees very well with the description of A. socialis, 

 as re-defined by Dr. Walcott from specimens obtained from the Para- 

 doxides-blandicus Zone of the Island of Borgholm (Sweden) ; but 

 our specimens are somewhat smaller than his, and in dimensions 

 and in most other respects approximate very nearly to the form 

 from the Paradoxides-forchhammeri Zone of Sweden assigned by 

 Linnarsson also to von Seebach's species, but since separated by 

 Dr. Walcott and described under the name of A. schmalensei. 



Other forms of Acrotreta may possibly occur with the above, but 

 I have been unable to separate them satisfactorily. 



Locality and horizon. — The upper section on the Shoot- 

 Rough Road, Comley ; from a gritty band of the Shoot-Rough- 

 Road Flags, 2 feet above the band containing Paradoxides dav 



Order PROTREMATA Beecher. 



Family Billingsellid^ Schuchert. 



Btllingsella lindstrcemi, var. salopiensis, nov. (PL XXYI, figs. 14 a 

 -17 c.)- 



1876. Cf. Orthis lindstrcemi Linnarsson, ' Brachiopoda of the Paradoxides Beds 

 of Sweden ' Bihang K. Svensk. Vetensk.-Akad. Handl. vol. iii,No. 12, p. 10 

 & pi. i, figs. 1-8, pi. ii, figs. 9-12. 



1905. Cf. Billingsella lindstrcemi Walcott, Proc. U. S. Nat. Mus. No. 1395 r 

 vol. xxviii, p. 238. 



Shell biconvex, rotundo-subquadrate to subcircular in outline, 

 wider than long, broadest at about the middle, cardinal angles 

 rounded. The surface is covered with fine, rounded, radiating costae 

 increasing usually by interpolation, the interspaces being rounded 

 and of about the same width as the costre. Fine concentric. 



