434 Dr. S. Woodward — Discovery of a Fossil Crab — 



cited as examples. These Limuloid Crustaceans have their earliest 

 representative (Neolimulus) in the Upper Silurian shales of Lanark- 

 shire, whilst their latest representative (Limulus) is actually found 

 living in the seas around China and Japan and on the East Coast of 

 North America at the present day. 



Professor L. G. de Koninck has just drawn my attention to a 

 remarkable fossil obtained by M. Persenaire from the Coal-shales of 

 the ' Belle-et-Bonne ' Colliery, near Mens, Belgium. 



This specimen, so kindly placed in my hands for examination by 

 M. de Koninck, represents, without doubt, the abdomen of a female 

 Crab (Decapoda-Brachyura). Unfortunately no other part of the 

 animal has been discovered ; we can only, therefore, conjecture 

 what its general form may have been from a consideration of the 

 portion preserved. 



The specimen, which is 12 millimetres in length, is preserved 

 upon the surface of a fragment of Coal-shale associated with the 

 impressions of Neuropteris heterophylla and Alethopteris lonchitidis. 



The abdomen is as nearly as possible perfect, and upon the surface 

 of the two pieces of shale, which correspond, we see clearly the 

 impression and counterpart of the fossil. 



Notwithstanding the small size of the specimen, M. Eutot, C.E., 

 has executed, under the direction of M. L. Gr. de Koninck, an 

 admirable figure, greatly enlarged, showing clearly all the salient 

 points of the fossil. By the kindness of the Council of the Koyal 

 Academy, I am enabled to reproduce this excellent figure (see 

 Plate XL). 



As in other short-tailed Decapod-Crustacea, the abdomen is seen to 

 consist of seven segments more or less completely ankylosed together, 

 as in the Leucosiadee. Unfortunately the external surface of the 

 central axis of the abdomen is wanting, but the divisions, strongly 

 indicated by raised lines, plainly show the area of each segment of 

 the median portion of the abdomen, and also clearly separate the 

 central axis from the widely expanded lateral border. 



The general form of the abdomen is oval save at its proximal 

 border, where it was attached to the cephalo thorax (PI, XL Fig. 1, 

 a h). This articular border [a b) measures 6 mm. in breadth, and 

 was evidently inserted under the posterior margin of the carapace to 

 about the depth of one millimetre. 



The two angles of the articular margin (a, a) project slightly 

 beyond the rest of the border, and evidently furnished two strong 

 points of attachment with the abdomen. 



The 1st segment, of which the articular border forms a part, is in 

 the form of a trapezium, having its broadest border directed forwards 

 and measuring 5 mm. in breadth, whereas the posterior border only 

 measures 3^ mm. ; the lateral borders of the segment are greatly 

 inclined. 



The central part of this segment bears two tubercles placed 

 symmetrically, one on either side of the mesial line, whilst three 

 small punctfe are placed near the centre of the posterior border. 



The axial or central part of the 2nd, 3rd, 4th, 5th, and 6th 



