596 



PISCES. 



[DIN. ECT. 



tumid ns, St. John & Worthen, 1875, Geo. 



Stir. 111., vol. 6, p. 339, St. Louis Gr. 

 DINICIITIIYS, N^wbeiry, 1873, Ohio Pal., 

 vol. 1, p. 313, ami vol. 2, p. 3. [E'y. 

 deins>s terrible ; ichthys, a fish.] Cranium 

 composed of thick bony phites, strength- 

 ened with internal arc-hes anchylosed 

 together, occipital bone in the lype 

 ppeci'S three inches in thickness; rel- 

 atively small maxillaries benring a 

 number of acufe, conicil, anchylosed 

 teeth, which interlocked with as'milar 

 series on the mandibles; premaxillari^s 

 large, strong, triangular plutesor teeih; 

 mandibles of great length, flattened and 

 spatulate behind, tnrnintr up anteriorly 

 to form a strong triangular tooth, wiio 

 its fellow of the opp )cite mandible, 

 interlocked with the great, diverg* nt, 

 premaxillary te< th ; vital parts of ihe 

 body covered with large, thick plates 

 whnh formed a carapace. Type D. 

 terrelli. 



hertzeri, Newberry, 1873, Ohio Pal., vol. 

 1, p. 316, Portage Gr. 



FIG. 1128. Diuichthys hertzer 



terrelli, Newberry, 1873-75, Ohio Pal., 

 vol. 1, p. 313, and vol. 2, p. 3, Por- 

 tage Gr. 



DiPLASi'is, Matthew, 1888, Can. Ree. Sci., 

 vol. 2, p. 251. [Ety. diplos, double; as- 

 pi*, shield.] Small, having plates on 

 the head, back, and sulep, and one ven- 

 tral plate; plates healing very fine 

 ridges. Type D. acadica." 



acadica, Mali hew, 1888, Can. Rec. Sci., vol. 

 2, p. 251, Up. Siluiian or Low. Devo- 

 nian. 



DIPI-ODUS, Agassi/, 1843, Recherches sur les 

 Poi>sons Fosi-ilep, t. 3, p. 204. [Ety. 

 diploof, double; O'/OMS, a tooth] This 

 name was u-ed by Kutinesque f->r a 

 genus of Sparidse in 1810, Indice d'Lit 

 tologia Siciliana. Teth having a flnt- 

 tened or rounded base, from which 

 spring two lateral and poim-finies a 

 small central denticle; each jaw bore 

 peveial hundred teeth in radiating rows, 

 the points projecting inward. They 

 belong to sharks possessed of f-pines, 

 described under the names of Oracan- 

 thus and Xenacanthus. Type D. gib- 

 bo&us. 



acinac(8, Dawson, 1860, Acad. Geol., p. 

 211, and Can. Nat. Geol., vol. 5, Coal 

 Meas. 



compressus, Newberry, 1857, Proc. Aoad. 

 Nat. Sci. Phil., vol. 8, p. 99, and Ohio 

 Piil., vol. 1, p. 335, Ceal Meas. 



duplicate, see Thrinacodus duplicatus. 



graoilis, Newherry, 1857, Proc. Arad. Nat. 



Sci. Phil., v.l. 8, p. 9!), and Ohio Pal., 



vol. 1, p. 335, Coal Mea*. 



incnrviis, see Thrina- 

 /\ codu-< incurvus. 



L \ latus, Newl>erry, 1857, 



1\^__-^^ 



w 



S.-i. Phil., vol. 8, p. 

 99, and Ohio Pal.. 



FlQ. 1127. Diplodus 

 hit us. 



vol. 1, p. 336, Coai 

 Meas. 



penetranp, Dawson, 

 18<>0, Acad. Geol,, 

 p. '21 Land Can. Nat. 

 and Geol., vol. 5, 

 Coal Meas. 



DIPTEIU-S, Sedawick & Murchison, 1835, 

 Geo. Trans., 2d ser., vol. 3. [Ety. 

 dtpleros, two-winged.] Diptera is an 

 order of insects establish! d by Linnaeus. 

 Small fusiform finhes ; heads com- 

 prehsed, tails heten>cercal ; two dorsal 

 tins opposite two simi- 

 lar anal fins, the 

 second of each the 

 larger ; a strongly 

 marked lateral line; 

 scales circular, thickest 

 in the middle, vari- 

 ously curved with con- 

 centric lines or longi- 

 tudinal ridges. Type 

 D. brachypvgopterus. 



sherwoodi, Newberry, 

 1875, Ohio Pal. vol. 2, 

 p. 61, Catskill Gr. 

 DRKPAXACANTIIUS, Newberry & Won hen, 

 1866, Geo. Snr. 111., vol. 2, p. 120. [Ety. 

 drepane, a sickle; akanllm, spine.] Fin 

 spines compressed laterally, gradually 

 tapering to an acute point, curved for- 

 ward ; anterior ma'gin with a row of 

 flattened or conical tubnclts; lateral 

 surfaces with tubercles in longitudinal 

 rows; posterior margin without hi/oks, 

 sometinvs with tubercles. Type D. 

 gemmatus. 



ar>crp, see Xy^tracanthus anceps. 



geniuiatus, Newberry & Worthen, 1866, 

 G o. Sur. 111., vol. 2, p. 123, Keokuk Gr. 



reveieus, St. John& Worthen, 1875, Geo. 

 Sur. III., vol. 6, p. 456, St. Louis Gr. 



follatm, nee Batacanthus stellatus. 

 ECIOSTK RACIIIS, Cope, 1S80, Pal. Bull. No. 

 32, p. 19. [Ely. fktofi, without; ort<on, 

 bone; rorhif, a ridge, backb< ne.] Base 

 of the hknll consists of oss lied para- 

 chordjils, which embrace the chorda 

 dorsalis posteriorly, and are continued 

 for a short distance posteriorly as a 

 tube; anteriorly the chopial groove is 

 open ; trabecu'se not Ohpified ; cranial 

 stiucture embryonic; above and in 

 front of the opening for the chorda the 

 neural canal enters the groove; para- 

 chordalsFubtriantMilar. TypeE. nitidns. 



ciceronius, Cope, 1883, Pal. Bull. No. 36, 

 in Pioc. Am. Phil. See., p. 628, Per- 

 mian. 



