c*~ 



No. 2. — Some New Ordovician TrUobitee. 



By Percy E. Raymond. 



The following brief descriptions of certain new species of trilobites 

 are abstracted from a larger manuscript, tin- publication of which 

 has been postponed to allow the preparation of adequate illustrations. 

 It has become necessary to use some of these names in .•mother con- 

 nection, hence this preliminary paper. 



Trixucleidae Emmrieh. 

 Trinucleus acervulosus, sp. now 



Entire test flattened, subcircular in outline, cephalon twice as wide as long, 

 with a narrow fringe. Glabella flask-shaped, narrow, bulbous in front, 

 constricted to a narrow, low neck behind. There are three pairs of glabellar 

 furrows beside the neck-furrow, two pairs showing as deep pits in the "neck," 

 and one pair as small indentations back of the middle of the "bulb." Fixed 

 cheeks evenly convex, without eyes or eye-lines. Surface of glabella and 

 cheeks reticulate. Fringe narrow, marked by radiating grooves separated 

 by rounded ridges of about their own width. In the bottom of each groove 

 are two pits, the anterior of which is the larger. At the genal angles the 

 fringe widens and is marked by a number of irregularly placed, small pits. 

 Xo specimen has been seen which retains genal spines, but they were undoubt- 

 edly present, as there is a long spine on one of the slabs. 



Thorax of six narrow segments of the usual form in the family. 



Pygidium a little more than twice as wide as long, somewhat angular in 

 outline on the posterior margin, nearly flat, with an abruptly deflected smooth 

 border. Axial lobe narrow, not strongly elevated, with twelve to fifteen 

 narrow rings separated by narrow, sharp furrows. Pleural lobes flat, with 

 eight or nine pairs of ribs, each bearing a broad deep furrow. 



Measurements: — The holotype is 19 mm. long, 19 mm. wide at the genal 

 angles; the cephalon 8 mm. long, thorax 5, and pygidium 6 mm. long. The 

 bulb of the glabella is 5 mm. wide; the axial lobe of thorax 3 mm. wide; the 

 pygidium 13 mm. wide. The fringe is 1 mm. wide, and there are twelve 

 grooves in 5 mm. Another specimen is 19 mm. long and 18 mm. wide, and a 

 third 12.5 mm. long and 12 mm. wide. 



This species, the first American representative of the genus to be 

 known from complete specimens, is more like Trinucleus diademata 

 (Ruedemann) than any other allied form, lluedemann's species 



