568 



CRUSTACEA. 



[STR. — TRI. 



Strobilepis, Clarke, 1888, Pal. N. Y., vol. 7, 

 p. 63. [Ety. strobilos, cone-shaped ; 

 lepis, scale.] Capitulum composed of 

 four vertical ranges of plates having in 

 general a trihedral form, but varying 

 in size and contour ; each plate articu- 

 lated with or overlapping the next pre- 

 ceding ; anterior extremity terminated 

 by a large, circular, conical plate ; plates 

 thick and ornamented. Type 8. spi- 

 nigera. 

 spinigera, Clarke, 1888, Pal. N. Y., vol.7, 

 p. 212, Ham. Gr. 



Stylonurus, Page, 1856, Geological Text 

 Book, p. 190. [Ety. stylos, a mast or 

 spar; oura, tail.] General form like 

 Eurypterus, but distinguished by the 

 peculiar development of the two pos- 

 terior foot pairs; these are alike, long, 

 thin, and consist of 9 segments, of 

 which the two last form a small claw; 

 the posterior pair reach to the middle 

 of the long posterior spine. Type 8. 

 powriei. 

 excelsior, Hall, 1884, 36th Rep. N. Y. St. 

 . Mus. Nat. Hist., p. 77, Catskill Gr. 



Symphysurus, Goldfuss, 1843, Neues Jahrb. f. 

 Mineral. [Ety. symphysis, growing 

 together; oura, tail.] Elliptical; genal an- 

 gles rounded ; cephalic shield semicircu- 

 lar, convex ; glabella convex, subquad- 

 rate, smooth, no lateral furrows ; eyes 

 lunate ; facial sutures arching in front 

 of the glabella, and cutting the posterior 

 part of the cephalic shield near the 

 genal angles; 8 thoracic segments; 

 pygidium somewhat semicircular, no 

 segments, border flattened. Type S. 

 lseviceps. 

 goldfussi (?), Walcott, 1885, Monogr. U. 8. 

 Geo. Sur., vol. 8, p. 95, Trenton Gr. 

 This species is founded on a glabella 

 with fixed cheeks, and probably it does 

 not belong to this genus. 



Telephus, Barrande, 1852, Syst. Sil. Boh. 

 [Ety. mythological name.] Glabella 

 strongly convex, margined by deeply 

 impressed bow-shaped furrows ; neck 

 segment tumid ; cheeks subtriangular, 

 or subrcescentiform, small posteriorly, 

 wider in front ; pygidium small, 

 strongly convex, hemispherical, mar- 

 gin tumid, axis with three segments. 

 Type T. fractus. Only recognized in 

 America by fragments of glabella, 

 americanus, Billings, 1865, Pal. Foss., vol. 

 1, p. 291, Quebec Gr. 



Terataspis, Hall, 1863, 16th Rep. N. Y. St. 

 Mus. Nat. Hist., p. 223. [Ety. teras, 

 marvel; aspis, shield.] Distinguished 

 from Acidaspis, which it resembles by 

 the prominent ellipsoidal frontal lobe 

 of the glabella, posterior spines of the 

 lateral lobes and nodes of the occipital 

 ring, and from Lichas by the spines of 

 the pygidium being themselves bearers 

 of lateral spines. Type T. grandis. 

 grandis, Hall, 1862, 15th Rep. N. Y. St. 

 Mus. Nat Hist., p. 82, and Illust. Devon. 



Foss., pi. 17, (Lichas grandis,) Scho- 

 harie grit. 



eriopis, Hall, 1863, (Lichas eriopis,) 16th 

 Rep. N. Y. St. Mus. Nat. Hist., p. 226, 

 and Illust. Devon. Foss., pi. 19, Up. 

 Held. Gr. 

 lhaleops, Conrad, syn. for Illaenus. 



ovata, see Illaenus ovatus. 

 TRiRATHRELLA,Hall, 1863, 16th Rep. N. Y. St. 

 Mus. Nat. Hist., p. 177. [Ety. diminu- 

 tive of Triarthrus.] Glabella elongate, 

 semioval, with the fixed cheeks wide 

 and spreading in the posterior limb, 

 and very narrow in front, an obscure 

 indentation at the margin ; general ex- 

 pression like Triarthrus. TypeT. auro- 

 ralis. 



auroralis, Hall, 1863, 16th Rep. N. Y. 

 St. Mus. Nat. Hist., p. 177, Pots- 

 dam Gr. 

 Trirathrus, Green, 1832, Monograph of 

 Trilobites, p. 87. [Ety. triarthrus, three- 

 jointed.] Subelliptical ; cephalic shield 

 somewhat semicircular or sublunate ; 

 glabella moderately convex, sides 

 straight, rounded in front, deeply trilo- 

 bate on each side by the lateral fur- 

 rows, with a prominent occipital groove 

 near the base, and occipital ring, from 

 the center of which a spine sometimes 

 arises; eyes small and placed on the 

 anterio-lateral margin ; free cheeks 

 forming a narrow rim ; thorax with 

 from 13 to 16 articulations ; central 

 axis convex, wider than the lateral 

 lobes; pygidium with 5 to 7 segments 

 in the axis and one or two less in the 

 lateral lobes. Type T. becki. 



becki, Green, 1832, Mono- 

 graph of Trilobites, p. 87, 

 and Pal. N. Y., vol. 1, p. 

 237, Utica Slate Gr. 



canadensis, Smith, 1861, 

 Can. Jour., vol. 6, p. 275, 

 Utica Slate Gr. 



fischeri, see Atops flscheri. 



glaber, Billings, 1859, Can. 

 Nat. and Geol., vol. 4, p. 

 382, and Can. Geol., p. 

 202, Utica Slate Gr. 



spinosus, Billings,1857,Rep. 

 of Progr. Geo. Sur. Can., 

 p. 340, and Can. Geol., p. 

 202, Utica Slate Gr. 

 Trimerus, syn. for Homalonotus. 



delphinocephalus, see Homalonotus delphi- 

 nocephalus. 



jacksoni, see Homalonotus jacksoni. 

 Trinucleus, Lhwyd, (or, as he spelt it, 

 Llhwydd,) 1698, Phil. Trans., vol. 20, p. 

 279. [Ety. trinucleus, three-kerneled.] 

 Cephalic shield highly convex, a wide 

 border impressed with several rows of 

 deep puncta and posterior angles, ter- 

 minating in spines ; glabella pyriform, 

 pointed behind, no lateral furrows; 

 cheeks convex ; no eyes or facial su- 

 tures; neck furrow distinct; thorax 

 with six articulations, axis narrow, 



Fio. 1062.— Tri- 

 arthrus becki. 



