MONOGRAPH 



OF THE 



FOSSIL MALACOSTRACOUS CRUSTACEA 



OF 



GREAT BRITAIISr. 



PART I. — Of those found in the London Clay. 



Sub-Order— OXYRHYNCHI. 



Family— MklKDM. 



Genus — Mithracia, Bell. 



Char. Gen. Testa subglobosa, tumida, rostro integro, supra sulcato. Orbita ovatse 

 supra bifissse. Antenna ad basin rostri insertcB. Pedipalpi externi caule interiore sulco 



longitudinali diviso, caule exteriore lineari. Abdomen maris ? fcemin^ ovatum, 



segmentis omnibus separatis. 



Species unica. Mithracia libinioides, miJii. Plate V, figs. 10 — 12. 



Bescr. Carapace tumid, nearly globular, as broad across the branchial region as it is 

 long, exclusive of the rosti'um, covered uniformly with small tubercles ; regions elevated, 

 distinct, the separating fm-rows narrow and smooth ; rostrum moderately projecting, entu-e, 

 with a small sulcus or depression above ; gastric region with distinct lobes ; the two proto- 

 gastric meeting at the median line and confluent ; the mesogastric triangular, and separated 

 by ai distinct furrow from the two metagastric, which a^e rather distinctly mai'ked ; the 

 urogastric twice as broad as it is long ; cardiac region gibbous in the centre ; hepatic region 

 rounded, raised and projecting at the margin ; the branchial very large, rounded, and tumid ; 

 orbits oval, slightly divided at the bottom into two portions by a small, transverse hue ; 

 antennae inserted beneath the base of the rostrum ; external footjaws with the inner stalk 



2 



