from the English Coal-measures. 



157 



indistinct traces of many small segments ; a group of three or more 

 large spines is placed, apparently, at the distal end of the first visible 

 segment of the peduncle. A pair of large impressions a little way 

 behind the antenna represent, in all probability, the mandibles. 



The thoracic region consists of seven free somites, although the first 

 (the second of the complete series of eight) is not perfect in any of 

 the specimens. Each somite is roughly semicircular in transverse 

 section, and has a pair of horizontally expanded pleural plates over- 

 hanging the attachment of the limbs. The antero-posterior length of 

 the somites increases from the first to the fourth or fifth, and the 



Ynr 



Pleurocaris annulatus. Partial restoration of the dorsal surface. x 6. 

 Based chiefly on specimens Nos. 18 and 23 in Mr. Egginton's 

 collection. Drawn by Miss Gr. M. Woodward. a. antennule (?) ; 

 a", antenna ; m. mandible ; II, second thoracic somite ; VIII, eighth, 

 thoracic somite ; 1, first abdominal somite ; 6, sixth abdominal somite. 



pleural plates, at first bluntly pointed and slightly produced forwards, 

 become more square-cut on the posterior somites. The dorsal surface 

 of the somites is marked with strong transverse ridges, giving the 

 body an annulated appearance and making the limits of the somites 

 hard to define. There appears to be one ridge about the middle of 

 each somite, and two others, which only become prominent on the 

 hinder somites, at the anterior and posterior margins respectively. 

 The thoracic legs, of which seven pairs can be made out, are all 

 similar and rather stout. No distinct traces of exopodites can be seen. 



