750 



ARTHROPODA 



PHYLUM VII 



Suborder B. HYMENOCARINA Clarke. 



Nebalia-like forms toith folded univalved carapace; rostrum wanting (1). 



Family 1. Hymenocaridae Salter. 



Body with eight to nine thoracic and abdominal seginents, and six caudal spines in 

 three fairs. 



Hymenocaris Salter (Fig. 1453). Carapace narrow in front, very broad posteriorly, 

 convex ; surface smooth or faintly lined. Cambrian ; Wales and British Columbia. 



Fig. 1452. 

 Nebalia geoffruyi M. Bdw. Recent ; Mediterranean. «/i. 



Fig. 1453. 



Hymenocaris vennicauda Salter. 

 Uppei' Cambrian ; Dolgelly, Wales. 

 i/i (after Salter). 



Several peculiar genera described by Walcott under the names of Hurdia, Tuzoia, 

 Odaraict, Fieldia and Garnarvonia, from the Middle Cambrian of British Columbia, 

 are doubtfully referred to this family. 



Suborder C. CERATIOCARINA Clarke. 



Carapace bivalved, with a median symphysis and a free rostrum. 



Family 1. Ceratiocaridae Salter. 



Carapace pod-shaped, smooth and without eye-nodes. 



Geratiocaris M'Coy {Entomocaris Whitf.) (Fig. 1454). Valves of carapace elongate, 



sub-ovate or sub-quadrate, 

 ^^ narrow in front, sub- 



VX* truncate, but not in- 

 j Bi^^ curved behind. Surface 

 without nodes or carinae. 

 ''tt Antennae (?) obscure; suj)- 

 posed gastric teeth large, 

 cuspidate. Rostrum 

 lanceolate. Body seg- 

 ments fourteen or more. 

 Fig. 1454. four to sBvcn extending 



Cemtiocaris papiUo Salter. Ordovician ; Ijanark- lieyond the carapace, SOme 

 sliiie. rt, Traces of antennules (?); m, Toothed plates, f flipiii witli nh^pnrp 

 possibly the mandibles ; r, Rostral J.late. l/j (after °^ U^e^n A\ llil ODhCUre 



H. Woodward). branchial ajjpendages 



(uropods). Telson long, 

 spinose on the edges ; two lateral appendages or cercopods. Abundant in Ordovician 

 and Silurian ; Europe and North America. 



