546 



CRUSTACEA. 



[ECH. — ELY. 



punctate, Hall, 1863, (Ceratiocaris punc- 

 tata,) 16th Rep. N. Y. St. Mus. Nat. 

 Hist., p. 74, Ham. Gr. 



pustulosa, Whitfield, 1880, Am. Jour. Sci. 

 and Arts, 3d ser., vol. 19, p. 38, Erie 

 shales. 



socialis, Beecher, 1884, Rep. of Prog. Pa. 

 Geo. Sur. PPP, p. 10, Chemung Gr. 



snblsevis, Whitfield, 1880, Am. Jour. Sci. 

 and Arts, 3d ser., vol. 19, p. 36, Erie 



Rlluflfl 



whitfieldi, Clarke, 1885, Bull. U. S. Geo. 

 Sur. No. 16, p. 45, Ham. Gr. 



wright ana, Dawson, 1881, (Equisetides 

 wrightenus,) Quar. Jour. Geo. Soc, vol. 

 37, p. 301, Portage Gr. 

 Echinognathus, Walcott, 1882, Am. Jour. 

 Sci. and Arts, 3d ser., vol. 23, p. 213. 

 [Ety. echino8, sea urchin; gnathos, jaw.] 

 Founded upon fragments ; endogna- 

 thary limbs (one or more pairs) formed 

 of eight or nine joints, six of which 

 carry long, backward curving spines, 

 articulated to their posterior side ; ter- 

 minal joint slender, elongate, acumi- 

 nate; surface of body with scale-like 

 markings. Type E. clevelandi. 



Cleveland!, Walcott, 1882, Am. Jour. Sci. 

 and Arts, 3d ser., vol. 23, p. 213, Utica 

 Slate Gr. 



Elm l'socKi'ii alus, Zenker, 1833, Beitrage 

 zur Naturgeschichte der TIrwelt, p. 51. 

 [Ety. fllipsis, ellipse; kephale, head.] 

 Broadly ovate; cephalic shield semi- 

 circular, depressed, without spines; 

 glabella subquadrangular, rounded in 

 front, without transverse furrows ; eyes 

 oblong, lunate, narrow, projecting out- 

 ward ; facial sutures short, commencing 

 at the anterior margin, in front of the 

 eyes, and curving over them toward the 

 posterior angles ; thoracic segments 

 twelve, axis nearly as broad as lateral 

 lobes; pygidium small, semicircular, 

 trilobed. Type E. horn. 



?curtus, Whitfield, 1877, Ann. Rep. Geo. 

 Sur. Wis., p. 58, and Geo. Wis., vol. 4, 

 p. 191, Potsdam Gr. Founded upon a 

 fragment of the cephalic shield, and 

 the generic reference is very doubtful. 

 Elliptocephala, Emmons, 1844, Taconic 

 System, p. 21. [Ety. ellipsis, ellipse; 

 kephale, head.] Ovate ; cephalic shield 

 lunate, more than twice as wide as long, 

 posterior angles produced in spines ; 

 groove and border on the anterior and 

 lateral margins ; glabella nearly equal 

 in width throughout, and marked with 



• three pairs of furrows ; eyes large, 

 elongate, semilunate, extending from 

 near the base of the shield more than 

 half way to the anterior margin ; hy- 

 postoma broadly ovate ; thirteen or 

 fourteen articulations in the thorax, 

 axis convex, lateral lobes flattened, last 

 segments directed backward ; pygidium 

 narrow, elongated, axis acutely pointed. 

 Type E. asaphoides. This generic name 

 can stand in accordance with rule n of 



the British Association of 1842, and the 

 established laws of nomenclature ad- 

 hered to by reputable scientists since 

 that time,' notwithstanding it is recom- 

 mended to naturalists in selecting 

 names to avoid such as too closely ap- 

 proximate words already adopted. It 

 is true the masculine form of the word 

 was preoccupied by Zenker, but the 

 same can be said of Goniophora of 

 Phillips, for Agassiz had preceded him 

 in using the word Goniophorus ; Schi- 

 zodon was used for a mammal before 

 King used Schizodus for a Lamelli- 

 branch ; Gray used Acrophylla before 

 Nicholson used Acrophyllum ; and we 

 might mention a hundred other in- 

 stances where generic names, differing 

 only in gender or termination, have 

 been introduced and accepted by the 

 best naturalists, and have come into 

 such general use as to constitute part 

 of the nomenclature of science. Ole- 

 nellus can not be used to supplant El- 

 liptocephala upon any ground of dis- 

 covery, definition, or law. 



asaphoides, Emmons, 1844, Taconic Sys- 

 tem, p. 21, and Pal. N. Y., vol. 1, p. 256, 

 Up. Taconic* 



gilberti, Meek, 1874, (Olenellus gilberti,) 

 Rep. Invert. Foss., p. 7, and Geo. Sur. 

 100th Mer., vol. 4, p. 44, Up. Taconic. 



howelli, Meek, 1875, (Olenellus howelli,) 

 Rep. Invert. Foss., p. 8, and Geo. Sur. 

 100th Mer., vol. 4, p. 47, Up. Taconic. 



iddingsi , 

 Wale ott, 

 1885, (Ole- 

 nellus id- 

 dingsi,) 

 M o nogr. 

 U. S. Geo. 

 Sur., vol. 

 8, p. 28, 

 Up. Ta- 

 conic. 



tho mpsoni, 

 Hall, 1859, 

 ( Olenellus 

 thomp- 

 soni,) 12th 

 Rep. N. Y. 

 St. Mus. 

 Nat. Hist., 

 p. 59, Up. Fig. 1003.— Elliptocephala 

 Taconic. thompsonl. 



undulostriata, Hall, 1847, (Olenus undu- 

 lostriatus,) Pal. N. Y., vol. 1, p. 258, 

 Up. Taconic. Poorly defined. 

 Elymocahis, Beecher, 1884, Rep. Pa. Geo. 

 Sur. PPP, p. 13. [Ety. elymos, pod; 

 karis, shrimp.] Carapace bivalve ; elon- 

 gate, longitudinally subquadrangular, 

 dorsal line nearly as long as the valves ; 

 margins thickened ; optic node near the 

 anterior end, behind which are two 

 elevations ; two segments in the ab- 

 domen; telson a short, broad spine, 

 with two lateral spines, crenulated on 



