42 FOSSIL MALACOSTRACOUS CRUSTACEA. 



Family— CRANGONIDiE ? 



Genus — ARCHiEooARABUs, M' Coy. 



Char. Gen. Testa antice depressa, plana, margine anteriore recto, denticulate-, rostro 

 parvo, bidentato ; sinu cervicali profundo, lato ; postice subcylindrica, regionibus 

 branchialibus latissimis. Oculi grandes, reniformes, pedunculis angustioribus. Pedes antici 

 magni, subclieliformes, digito mobili longo, curvo, ad marginem anteriorem manus opposito. 

 Pedes reliqui filiformes, inermes, subtriedri. Abdomen semicirculare, glabrum. Sternum 

 segmentis in medio bituberculatis. 



Species unica. ArchjEocarabus Bowerbankii, M'Coy. Plate XI, figs. 1 — 5. 

 Akoh;eocarabus Bowerbankii, 3£'Coy. Ann. Nat. Hist., 1. c. 



Descr. Carapace about twice as long as it is broad, covered with oval, subsquamiform, 

 flattened tubercles, their blunt apices directed forwards ; cervical furrow deep and broad ; 

 the cephalic arch, or portion anterior to the cervical furrow, flattened, with a high, abrupt 

 carina on each side, which is polished, and armed with two strong spines ; the scapular 

 arch or posterior portion of the carapace, with the tubercles much larger than those on the 

 anterior portion, those on the back being the largest of all ; the cardiac region elevated, 

 the branchial very broad, wholly lateral, and placed almost perpendicularly ; the branchio- 

 cardiac furrow distinct, smooth, and polished. Abdomen, including the caudal fin, 

 nearly twice as long as the carapace, semi-cylindrical, smooth, slightly punctated ; epimeral 

 pieces abruptly narrowed, triangular, falcate, curved backwards, and acute at the apex ; 

 lateral plates of the tail nearly three times as long as they are broad, slightly curved, 

 granulated ; anterior feet broad, compressed ; the hand very broad, expanded towards the 

 anterior extremity, with a broad, longitudinal depression ; the anterior margin truncate, 

 toothed, the extreme joint or moveable finger curved, longer than the anterior truncated 

 margin of the hand, to which it is opposed for prehension ; the arm compressed, broad, 

 longer than the hand ; the remaining legs nearly triedral, smooth, and polished ; sternum 

 triangular, contracted at the anterior part, each segment having a double tubercle in 

 the centre. Eyes very large, reniform ; the peduncle very short, and not one third 

 as broad as the eye. 



Length of the carapace, about 3 inches. 



