440 //. Woodward — Notes on Palceozoic Crustacea. 



tinctly defined as in B. hellulus, but the central axis is more strongly- 

 marked. The eyes are not very well seen, but they occupy the same 

 relative position on the margin of the raised glabella as in B. hellulus. 



The abdominal division consists, as in the other species, of three 

 coalesced segments, which are however only indicated by three 

 marginal serrations. 



The tail-spine (telson) is not preserved, but its articulation with 

 the abdomen is strongly marked. 



Greatest length of entire body, 9 lines. 



G-reatest breadth of head-shield, 1 inch. 



Length of five free thoracic segments, 3 lines. 



Breadth of first free thoracic segment, 10 lines. 



Breadth of fifth free thoracic segment, 5 lines. 



Breadth of central axis of body-segments, 2-| lines. 



I have named this species after Mr. Charles Konig, the original 

 founder of the genus, and for many years the Keeper of the Geo- 

 logical and Mineralogical Collections in the British Museum. The 

 original specimen is preserved in the British Museum, and was 

 obtained by C. Ketley, Esq., from the Dudley Coalfield. 



2. Prestwichia BirtivelU, H, Woodw., sp. nov., PL X., Figs. 9 

 and 10. 



For a knowledge of this small but well-marked and very charac- 

 teristic species of Coal Limiilus I am indebted to Mr. Thomas 

 Birtwell, of Gawthorpe Gardens, Padiham, Lancashire, who obtained 

 it from the Coal-Measures at the Cornfield Pit on the south bank of 

 the Eiver Calder, near Padiham. It was from this pit that the new 

 Arachnide (Architarbus suhovalis, H. Woodw.) described in our last 

 Number, p. 385, was obtained by Mr. Birtwell. 



This new species (of which there are two examples, both figured 

 in our Plate) exhibits the most complete anchylosis of its body- 

 segments of any of the Coal Limuli. The entire body measures 

 8 lines in length, and 8 in greatest breadth ; of this the head-shield 

 measures 4 lines in length, and 8 in breadth ; the anterior (thoracic) 

 part of the post-cephalic shield is 6 lines broad, diminishing to 2 

 lines near the posterior (abdominal) part ; length of the thoracico- 

 abdominal somites 4 lines. The telson measured 4 lines in length. 

 The head-shield is very tumid, the posterior genal angles are not 

 produced ; the glabella is divided down the centre by a slender 

 ridge, its front border (as in most other species) forms two arches, 

 between which and in the front of the head-shield, the larval eye- 

 spots are seen ; the small compound eyes are placed midway upon 

 the lateral border of the glabella. 



The divisions of the thoracico-abdominal segments are only faintly 

 indicated along the central axis of the body ; the margin does not 

 show the usual serrations or spines, as in the other species ; but the 

 number of segments appears to have been the same. The coalesced 

 abdominal segments were marked by a very prominent spine or 

 tubercle, the top of which has however been broken off. 



I have named this specimen Frestwichia BirtioelU, after its dis- 

 coverer, Mr. Thomas Birtwell, in whose collection the specimens are 

 preserved. 



