544 



CRUSTACEA. 



[dic— dip.. 



granulosus, see Ptychaspis granulosa, 

 liisingeri, Billings, 1865, Pal. Foss., vol. 1, 



p. 196, Quebec Gr. or Up. Taconic. 



inexpectans, Walcott, 1885, Monogr. U. S. 



Geo. Sur., vol. 8, p. 90, Quebec Gr. or 



Up. Taconic. 



iole, Walcott, 1885, Monogr. U. S. Geo. Sur. 



vol. 8, p. 43, Potsdam Gr. or Up. Taconic. 



latifrons, Sliumard, 1863, Trans. St. Louis 



Acad. Sci., vol. 2, p. 101, Potsdam Gr. 

 lodensis, Whitfield, 1880, Ann. Rep. Geo. 

 Sur. Wis., p. 51, and Geo. Wis., vol. 4, 

 p. 189, Potsdam Gr. 

 magnificus. Billings, 1860, Can. Nat. and 

 Geo., vol. 5, p. 301, Quebec Gr. or Up. 

 Taconic. 

 marcoui. Whitfield, 1884, Bull. Am. Mus. 



Nat. Hist., vol. 1, p. 139, Up. Taconic. 

 marica, Walcott, 1886, Monogr. U. S. Geo. 



Sur., vol. 8, p. 44, Potsdam Gr. 

 megalops, Billings, 1860, Can. Nat. and 

 Gfo., vol. 5, p. 301, Quebec Gr. or Up. 

 Taconic. 

 mini#c>nsi*, see Ptyebaspis miniscensis. 



minnesoten sis, 

 Owen, 1862, Rep. 

 Wis., Iowa, and 

 Min.,p. 574, Pots- 

 dam Gr. 

 minnesotensis 

 var. limbatus, 

 Hall, 1888, 16th 

 N. Y. St. 

 Nat, Hist., 

 Potsdam 



Fig. 909.— Divttilocepb*. 

 lus niiuuenotensls. 



Rep. 



Mus 



)•■ 141, 

 Gr. 

 misa, Hall, 1863, 

 16th Rep. N. Y. 

 St. Mus. Nat. 

 Hist., p. 144, Pots- 

 dan: Gr. • 

 missisqnoi, Billings, 1865, Pal. Foss., vol. 



1, p. 199, Quebec Gr. or Up. Taconic. 

 muliicinctus, Hall & Whitfield, 1877, U. S. 



Geo. Expl. 40th Parallel, vol. 4, p. 226, 



Potsdam. Gr. 

 nasut us, Walcott, 1885, Monogr. U. S. Geo. 



Sur., vol. 8, p. 44, Potsdam Gr. 

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



Mus. Nat, Hist., p. 146, Potsdam Gr. 

 oweni, Billings, 1860, Can. Nat. and Geo., 



vol. 5, p. 301, Quebec Gr. or Up. Taconic. 

 pauper, Billings, 1865, Pal. Foss., vol. 1, 



p. 200, Quebt c Gr. or Up. Taconic. 

 pepinensis, Owen, 1852, Geo. Wis., Iowa, 



and Minn., p. 574, P-itsdam Gr. 

 planifrons, Billings, 1860, Can. Nat. and 



Geo., vol. 5, p. 301, Quebec Gr. or Up. 



Taconic. 

 pogonipensis, Hall & Whitfield, 1877, 



U. S. Geo. Expl. 40th Parallel, vol. 4, 



p. 243, Potsdam Gr. 

 quadriceps, see Olenoides quadriceps, 

 richmondensis, Walcott, 1885, Monogr. 



U. S. Geo. Sur., vol. 8. p. 41, Potsdam Gr. 

 roemeri, Shumard, 1861, Am. Jour. Sci., 



vol. 32, p. 220, Potsdam Gr. 

 selectus, Billings, 1865, Pal. Foss., vol. 1, 



p. 199, Quebec Gr. or Up. Taconic. 



sesostris, see Ptychaspis sesostris. 

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



Mus. Nat. Hist., p. 143, Potsdam Gr. 

 wahsatchensis, see Olenoides wahsatch- 

 ensis. 



Dicranurus, syn. for Acidaspis. 

 hamatus, see Acidaspis hamata. 



Dionidk, Barrande, 1847, in Lith. Proc. 

 [Ety. from the mythological name 

 Dione.'] Body oval, tapering behind, 

 trilobed, faintly convex; cephalic shield 

 short, wide, semicircular, or crescenti- 

 form, produced at the postero-lateral 

 angles into spines ; glabella short, wide, 

 strongly convex, smooth, no lateral fur- 

 rows ; two longitudinal furrows, mak- 

 ing it trilobate; cheeks wide, with per- 

 forated margin ; no eyes ; no facial 

 suture; hypostoraa elliptical, with two 

 bow-shaped wings in front, and poste- 

 rior margin entire; six thoracic seg- 

 ments, with nodes on each side of the 

 axial lobe ; pygidium subtriangular, 

 rounded behind axis, with numerous 

 segments, and lateral lobes with radial 

 furrows. Type D. formosa. 

 (?) perplexa, Billings, 1866, Catal. Sil. Foss. 

 Antic, p. 67, Anticosti Gr. 



Dipeltis, Packard, 1885, Am. Nat., vol. 

 19, p. 291. [Ety. dis, double ; peke, small 

 shield.] Cyclus-like in form ; suborbic- 

 ular, flattened, disk-like, sloping from 

 the median area to the edge; divided 

 in two parts, a cephalic shield and ab- 

 domen ; integument thin, showing no 

 segments. Type D. diplodiscus. 

 diplodiscus, Packard, T885, Am. Nat., vol. 

 19, p. 291, Coal Meas. Poorly defined. 



Dipleura, Green, syn. for Homalonotus. 

 dekayi, see Homalonotus dekayi. 



Dipuchnites, Dawson, 1863, Am. Jour. Sci. 

 and Arts, 3d ser., vol. 5, p. 19. [Ety. 

 diploos, double ; ichno*, foot-print,] Con- 

 sisting of two rows of impressions, each 

 about an inch long and one-fourth of 

 an inch wide, placed close together, 

 while the rows are six inches apart, 

 and the intermediate space smooth, as 

 if a flat body had been drawn over it. 

 Type D. aenigma. 

 senigma, Dawson, 1863, Am. Jour. Sci. and 

 Arts, 3d ser., vol. 5, p. 19, Coal Meas. 



DlPLO stylus, a £ 



Salter, 

 1863, Quar. 

 Jour. Geo. 

 Soc, vol. 

 19, p. 76. 

 [Ety. Dip- 

 Lostylu s , 

 double 

 tail, in al- 

 lusion t o 



the two FlG. KM).— Diplostylusdawsoiji. 

 pairs of ap- a > Tail, oat. size; b, terminal 

 pendages Joint, enlarged. 

 to the telson.] Carapace unknown ; 

 body segments arched, and with minute 

 pleurae ; tail segment large, triangular, 



