SYNOPSIS OF GENERA. 



MX 



Genus DIPTE KOC ARIS, Clarke. 1883. 



1553. Dipterocaris, Clarke. Amer. Jour. Science. 



1853. Dipterocaris, Etheridge, Woodward and Jones. Rept. Committee Foss. Phyllop. 



1854. Dipterocaris, Jonbs and Woodward. Geol. Magazine. 



1554. Dipterocaris, Etheridge, Woodward and Jones. Second Rept. Committee Foss. Phyllop. 

 1885. Dipterocaris, Clarke. Dev. Faunas Ontario county. 



1885. Dipterocaris, Etheridge, Woodward and Jones. Thii-d Rept. Committee Foss. Phyllop. 

 1885. Dipterocaris, Zittel. Handb. d. Palseontologie. 

 1SS(J. Dipterocaris, Clarke. Geol. Succession in Ontario Co 



Diagnosis. Carapace in one piece, ovate in general outline; normally with 

 an elevated dorsum and sloping sides. Each extremity is strongly notched, 

 dividing the carapace into two hroad ala. connected hy a narrow isthmus which 

 shows no evidence of a dorsal suture or anchylosis. Surface ornamented by 

 concentric elevated lines or wrinkles. 



The true organic character of the bodies included under the genera Spathio- 

 caris and Dipterocaris and allied forms, from the Devonian horizons of Great 

 Britain and Europe, ha.s been a subject of some debate among recent writers. 

 A diversity of opinion has arisen from the fact that while some of the species 

 included under the closely related genera Peltocaris, Salter, Aptychopsis, Barrande, 

 Discinocaris, Woodward, Aspidocaris, lleuss, Cardiocaris, Woodward, Ellipsocaris, 

 Woodward, and Spathiocaris, Clarke, have afforded 

 indisputable evidence of a free rostral plate cover- 

 ing the anterior cleft, e. g., Peltocaris aptijchoides, 

 Salter; Aptychopsis prima, Barrande; Cardiocaris 

 Rameri, Woodward ; Discinocaris Browniana, Wood- 

 ward ; since the original description of the species 



as Crustacea, Others have been found in the body Discinocaris Browniana, Woodward. 



chamber of a single species of Gonialites (G. intumescens) (Cardiocaris lata, Wood- 

 ward, Spathiocaris Kmneni, Clarke, both from the middle Devonian limestones 

 at Bicken, Westphalia). From this fact, together with the similarity of these 

 latter bodies in many respects to the aptychi of Mesozoic Cephalopoda, and 

 their agreement in outline with the transverse section of the body chambers in 

 which they have been found, there is no doubt that these two species at least 

 have had some organic connection with the cephalopoda, serving a similar 



