436 M. E. Rigaux — The Brachiopoda of the Boulonnais. 



believe may have likewise belonged to a Brachyuran Decapod from 

 the Pendleton Colliery, near Manchester, I have felt greater confi- 

 dence in the determination of the Belgian fossil, and in considering 

 it as constituting the abdomen of a true crab. 



The most ancient short-tailed crab hitherto known is the PalcB- 

 inaclius longipes from the (Forest Marble) Great Oolite, Malmesbury, 

 Wiltshire, which I described in 1866.^ 



The discovery of this fossil, therefore, removes the origin of the 

 Decapoda-Brachyura to an epoch in geological time far anterior to 

 that hitherto recorded, and serves to show well how little reliance 

 can be placed upon merely negative evidence. 



In the absence of other remains which might serve to complete 

 our knowledge of the animal we have ventured to describe, it would 

 be premature to attempt to show its affinities with any existing form 

 or to give it a name indicative of its relationship. I prefer, therefore, 

 to designate it as Brachypyge carbonis, for in the event of the dis- 

 covery of more complete remains which would enable us satis- 

 factorily to determine the modern representatives of this interesting 

 species, the name (if calculated to mislead) would of necessity at 

 once become a bui'den to synonymy. 



EXPLANATION OF PLATE XI. 

 Brachypxjge carbonis, H. "Woodw. From the Coal-measures, ' Belle-et-Bonne ' 

 Colliery, near Mons, Belgium. 



Fig. 1. — Figure enlarged ten times. I Fig. 2. — Figure of the natural size. 



II. — The Fossil Bkachiopoda of the Lowee Botjlonnais. 



THE following carefully and elaborately prepared list of the fossil 

 Brachiopoda of the Lower Boulonnais has been forwarded to 

 the Editor for publication by his esteemed friend and frequent con- 

 tributor Thomas Davidson, Esq., F.R.S., who writes as follows : — 

 "At my request M. E, Eigaux (51, Grande Eue, Boulogne-sur-mer, 

 France) has been engaged for more than two years in drawing up 

 a complete summary of all the Brachiopoda that are to be found in 

 the various formations com^DOsing the Lower Boulonnais. 



" This list is of great importance as so many of the beds correspond 

 completely with our own, and are extremely rich in a paleeonto- 

 logical point of view. Thomas Davidson. 



''3, Leopold Eoad, Brighton, Tth August, 1878." 



List of Fossil Brachiopoda found in the Lower Boulonnais. 

 By Monsieur E. Eigaux. 

 Devonian. 

 Terehratula saccidus, Mart. Very common in the shales of Beaulieu, 



scarce in the Ferques limestone. 

 Spirigera concentrica, D'Orb. Very common in the. highest beds of 



the Ferques limestone ; Blacourt, Beaulieu. 

 Spirigera Pelapayensis, D'Orb. Eather common in the shaly beds 

 over the Blacourt limestone in the Cedule quarry, scarcer in the 

 Ferques limestone at Blacourt. 



1 Quart. Journ. Geol. Soc. vol. xxii. p. 494. 



