10 FOSSIL MALACOSTRACOUS CRUSTACEA. 



longitudinally divided by a furrow, outer stalk linear ; female abdomen oval, the sixth 

 segment as long as the fourth and fifth together, the seventh triangular. 

 Length and breadth of the carapace 09 inch. 



Obs. The above description is taken from several specimens in Mr. Bowerbank's 

 collection, and in the British Museum. In none of them are there any remains of the 

 limbs. In one only, a female, is the abdomen existing, and in another the body is 

 sufficiently perfect to give the form of the rostrum, and the above imperfect details of 

 the antennas, orbits and external footjaws. These data are sufficient to indicate a 

 marked affinity to several genera of the family Maiadse, to which the fossil evidently 

 belongs ; and whilst in some respects the structure appears to point to a near relation to 

 Miihrax, in others it appears to approximate to Libinia. 



This is the only instance known of any fossil representative of the extensive tribe 

 of the Oxyrhynchi ; and this circumstance renders it one of the most interesting additions 

 we have made to our knowledge of extinct Crustacea. Professor Milne Edwards has 

 the following observation on this subject.* "Jusqu' ici nous ne connaissons aucun 

 Crustace fossile que Ton puisse regarder, avec quelque certitude, comme appartenant a la 

 famille des Oxyrhinques." The species referred by Desmarest to the genus Inachus, 

 is, as will be shown, a species of the Anomurous group, and is nearly allied to JDromia. 

 It will be found described under the name of Dromilites Lamar ckii, and is the 

 Basinotopus of M'Coy. It has no relation whatever to the present family, and thus, until 

 the present instance, the observation of Edwards remained unexceptional. f 



All the specimens known are from the Isle of Sheppey. 



Sub-Order— CYCLOMETOPA. 

 Family— CANC¥RIDM. 



Genus — Xanthopsis, M'Coy. 



Char. Gen. Testa ovata, supra nodosa, fronte quadrilobo. Orbita latae, angulis 

 lateralibus et inferiore prominentibus. Fosses antennaria ovatae, apertae. Antenna 

 externa articulo basali bis longiore quam latiore, lateribus parallelis : interna articulo 

 basali late triangulari, antice truncato, ad frontem attingente. Pedipaljpi externi caule 



* 'Hist. Nat. des Crust.,' tome i, p. 271. 



j* Since the above was written, Mr. Woodward lias pointed out to me in the British Museum a small 

 specimen (a Crustacean) from the Gault, which appears to belong to the Oxyrhynchi, and which would 

 constitute a second exception. I have also been favoured with two specimens from the collection of 

 M. Edwards, one from Colwell Bay, in the Isle of Wight, the other from Brockenhurst, Hants, which may 

 possibly prove to belong to the Oxyrhynchi, but which require further examination. These will be 

 further considered at a future time. 



