1889.] NATURAL SCIENCES OF PHILADELPHIA. 167 



pygidium and its central row of nodes along the axis of the pygi- 

 dium. 



Mr. Edward Forbes, [Mem. Geol. Survey United Kingdom, Dec. 

 2, 1849, pi. X] has suggested the new generic name of Brachampyx 

 for species like the above, with six thoracic segments and short and 

 rounded heads, to separate them from species of the genus Ampyx 

 with five thoracic segments and longheads. Length of largest 

 specimen 27 2 mm., head 11 mm., thorax 82 mm., pygidium 8 mm., 

 greatest width of tail 20 mm., length of pygidium, small specimen, 

 6 mm. 

 Encrinus varicostatus, Walcott. 



Encrinurus varicostatus, Walcott, 1877, Adv. Sheets 31st. Rept. 

 N. Y. State Cab. Nat, Hist. p. 16 ; 31st. Rept. N. Y. State Cab. Nat. 

 Hist. p. 69. 



Cryptonymus varicostatus, Vodges, 1878, Mon. genera Zethus, 

 Encrinurus and Cryptonymus, p. 27. 



Encrinurus excedrinus, Safford, 1869, Geology Tennessee, p. 290. 

 £^j^\ The, only known part of this species is the 



C^\N pygidium, it is subtriangular in outline, width 

 slightly greater than its length, convex, axis 

 tapering to a blunt point and marked with 13 

 or more rings extending entirely across it as far 

 as the last pleurre, with possibly 6 or 8 more. 

 The sides are marked with 6 ribs, decreasing in length gradually, 

 the last pair coalescing with the axis, and separated from it by a 

 shallow groove. Surface granular, without nodes. Length of 

 largest specimen 7 mm., width 7* mm. Geological positions and 

 locality, Trenton limestone, Lebanon, Tenn., Cedar Glades. 



Mr. C. D. Walcott says that his specimens have about 16 smooth 

 rings; the anchylosing of the posterior rings renders it difficult to 

 determine the exact number. 



Trenton limestone, Mineral Point, Beloit, &c, Wisconsin. 



Chasmops Troosti, Safford. 



Dalmanites Troosti, Safford, 1869, Geol. Tennessee, p. 290. 



Description : General form narrowly ovate, convex, head semi- 

 circular, genal angles produced into spines extending to the fifth 

 thoracic segment. Eyes prominent, faceted glabella large, clavate. 

 The specimen! is not in condition to record the minor details of the 

 head. Thorax with 11 segments, axis prominent, convex, tapering 



