754 



ARTHROPODA 



THYLUM VII 



Suborder E. DISCINOCARINA Clarke. 



Sub-circular or oval shields with a triangular rostrum filling an anterior notch. 

 Surface ornamented with raised- concentric lines. Substance chitinous. 



Family 1. Discinocaridae AVoodward. 

 Test convex, sometimes mesially ridged ; in a single piece. 



Discinocaris Woodw. Shield sub-circular, rostral notch and rostrum angular. 

 Abdominal segments and caudal spines have been referred to this 

 genus by Jones and Woodward. Silurian ; Great Britain, 

 Bohemia. 



Aspidocaris Reuss. Similar to Disrinocaris. Raibl Beds 

 (UpiJer Trias) ; Hallstadt. 



Dipterocaris Clarke (Fig. 1460). Shield with a deep posterior 

 notch, sliorter than the anterior or rostral notch. Sides of shield 

 sloping. Silurian ; Scotland. Ui^per Devonian ; New York. 



Fig. 14(50. 



Diptfivcaris ivtustus 

 d'Aich. and Verii. Pe- 

 vonian ; Eifel. i/j. 



Peltocaris Salter. 

 Abdomen unknown. 



Family 2. Peltocaridae Salter. 



notch and plate. 



A numbei' 



Shields mesially sutured. 



Circular shields with a rounded rostral 

 Ordovician ; Great Britain. 

 Apityrhopsis Barr. (Fig. 1461). Like Peltocaris, but with the 

 rostral notch angular. Silurian ; Bohemia and Great Britain. 



Pinnocaris Etheridge. Similar to Dipterocaris, but bivalved. 

 Ordovician ; Scotland. (P. lapirorthi Etheridge jun.) 



Fki. 1461. 



AptyrhopsU j)7'i))i«.s 

 Addendum. '^arr. ordovician (D) ; 



Branik, Bulipniia. l/i 

 „ . . ^ ,. . _,. - ,„,-,> (af'tei- Bai'Kin(]e). 



ot generic names, sucJi as vardiocaris (rig. 1462), 



Ellipsocaris, Pltoladocaris Woodward, and Sputhiocaris Clarke, 

 have l^een applied to Devonian fossils whicli closely resemble the 

 Silurian Discinocaris, of whose Crustacean nature there seems to 

 be 110 doubt. Some of these l)odies, however (Garcliocaris), have 

 been found in the living chamber of Goniatites {G. intumescens), 

 and have undoubtedly served as opercula or aptychi of these 

 Cejahalopods ; of others the nature is not fully understood. 

 Lisgocaris Clarke is not a Crustacean ; Gryptocaris Barrande is 

 })robably the operculum of a Hyolithoid ; Myocaris Salter is 

 stated to be a Pelecypod ; Proricaris Baily was founded on 

 parts of Geratiocaris ; Grescentilla and Pterocaris Barrande are 

 doubtfully Crustacean. 



Fia. 1462. 



Vardiocaris (Anajiti/- 

 rhns?) rocmeri Woodw. 

 Upper Devonian ; 

 Blidesheini, Eifel. Vi- 



Series 11. EUMALACOSTRACA Grobben. 



Abdomen of six somites, all of which may hear appendages, and a telson ivhich 

 never bears movable furcal rami. Thoracic limbs rarely all similar, fi/picalhj 

 pediform. 



The remains of Crustacea presenting the primitive " caridoid fades," as 

 described above, occur in the Carboniferous, and it may be that the Eumala- 

 costraca had their origin in that epoch. If certain Devonian fossils are 



