A W. Shuler — New Ordovician Eurypterid. 551 



Art. XXXYI. — A New Ordovician Eurypterid ; by Ellis 



W. Shuler. 



During the summer of 1914, the writer collected fossils from 

 the Bays sandstone at various points along Walker Mountain 

 in southwestern Virginia. The collection at Lyons Gap 

 yielded a few Eurypterid fragments. This is one of the best 

 known localities for collecting in the Bays sandstone. Prof. 

 J. J. Stevenson visited the locality in 1881 and secured a 

 number of fossils among which were " Ambonychia radiata" 

 and " Rliynconella capax " (= Orthorhynchula Imneyi), and 

 since that time it has been visited by a number of other geolo- 

 gists. These facts are mentioned because the Bays sandstone 

 formation is for the most part unfossiliferous in Walker 

 Mountain. The fossiliferous localities are limited to the south- 

 western section of the mountain along a band about twenty 

 miles in length. 



At Lyons Gap the fossil-bearing bed is about ten feet in 

 thickness and occupies approximately the middle of the Bays 

 formation, ninety feet below the Clinch sandstone. The point, 

 however, of separation of the Bays sandstone from the Sevier 

 shales below is a somewhat arbitrary one. The bed is an 

 argillaceous sandstone which has a pronounced brick red color. 

 It seems worthy of note that the bed carrying marine fossils is 

 distinctly redder than the non-fossiliferous part of the sand- 

 stone. The southwestern section of the Bays sandstone along 

 Walker Mountain, carrying the fossiliferous horizon, is also, 

 on the whole, a deeper red than the section along the moun- 

 tain to the northeast, which is practically barren of fossils. 



Stylonurus ( Ctenopterus) f alveolatus sp. n. 



The Eurypterid fragments consist of parts of four post-oral 

 limbs ; a part of the telson spine with the impression of two 

 abdominal segments, and a fragmentary carapace. 



The best preserved fragment is that belonging to the second 

 or third endognathite, fig. 1. It consists of three segments, 

 all of which, after making allowance for mashing due to the 

 conditions of preservation, show a distinct dorsi-ventral flatten- 

 ing. The articulation of the joints is such as to permit flexing 

 movements downward and backward, an arrangement which 

 suggests an adaptation of the limb to swimming. The indi- 

 vidual segments are distinctly elongated, being on the average 

 twice as long as wide. The lengths of the successive segments 

 beginning with the proximal one are : 16 mm , 16 mm , and 20 mm . 

 The corresponding widths are : 10 rara , 8 mm , and 6 mm . 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 233. -May, 1915. 

 36 



