hiii SYNOPSIS OF GENERA. 



Family, Rhinocarid^e. 

 Genus RHINOCARIS, nov. gen. 

 Diagnosis. Cephalothorax univalvular, later- 

 ally appressed ; outline as in Ceraliocaris. An- 

 terior extremity produced into a narrow, ver- 

 tically flattened prora continuous with sub- 

 stance of the carapace. The axial line of the carapace bears a low ridge along 

 which it shows no inclination to separate when laterally compressed. Surface 

 smooth or with one or more lateral carina), and ornamented by finely elevated 

 lines, granules or tubercles. Abdomen composed of not less than four smooth 

 sub-cylindrical somites. Post-abdomen bearing three spines, of which the telson 

 is elongate and conical and the cercopods flattened. 



This genus includes a series of forms which may tentatively be regarded as 

 Phyllocarida, but which represent a type of crustacean structure hitherto unre- 

 alized, taxonomically intermediate between the univalve Phyllocarida, 

 Hymenocaris and Dictyocaris, and the Macrourous Decapoda. 



Family, Discinocarid^e. 

 Genus SPATHIOCARIS, Clarke. 1882. 



I v ^-'. Spathiocaris, Clarke. Amev. Juurn. Science. 



lss;:. Kputh'itirnrts, Packard. Monog. North Amer. Phyllop. Crustacea. 



18S:t. Spathiocaris, Etheridge, Woodward and Jones. Rept. Committee Foss. Phyllop. 



1S84. Spathiocai'is, Clarke. Neues Jahrb. fur Mia. 



1884. Spathiocaris, Dames. Neues Jahrb. fur Min. 



1884 Spathiocaris, Von Koenen. Neues Jahrb. fiir Min. 



1884. Spathiocaris, Etheridge, Woodward and Jones. Second Rept. Committee Foss. Phyllop. 

 1^1. Spathiocaris, Jones and Woodward. Geol. Magazine. 



l ss "' caris, Clarke. Devon. Faunas Ontario county. 



L885. Spathiocaris, Etheridge, Woodward and Jones. Third Rept. Committee Foss. Phyllop. 



1885. Spathiocaris, Dames. Neues Jahrb. fur Min. 



1885. Spathiocaris, Zittel. Handb. d. Pateontologie. 



1886. Spathiocaris, Clarke. Geol. Succession in Ontario Co. 



Diagnosis. Carapace in one piece, elliptical, sub-conical and patelloid ; apex 

 situated at or near one focus of the ellipse. The cephalic cleft begins just in 

 fronl of the apex and slowly widens to the anterior extremity. Surface orna- 

 mented with closely set concentric lines and usually with fine radii on the ante- 

 rior and posterior portions. 



