AQUATIC ANIMALS OF THE COAL. 207 



The following arc Mr Salter's descriptions of these interesting 

 crustaceans, taken from his paper, Journal of Geol. Society, vol. 



xi\. : — 



u Diplostylus, gen. now 



" Carapace unknown. Body segments arched, and with minute 

 pleura. Tail segment large, triangular, spinosc, with two pairs of 

 simple ovate appendages. 



" Diplostylus Dawsoni, spec. nov. (Fig. 49). 



u The portion preserved consists only of five rings and the broad 

 telson; and these together are three-fourths of an inch long, and less 



Fig. 49. — Diplostylus Dawsoni. 





(a) Tail, nat. size ; (I) terminal joint enlarged. 



than half an inch broad at the widest part. The telson is somewhat 

 narrower than the body-rings, broad above, and pointed behind, 

 where it is notched into three spines, the centre one very short, the 

 two on each side of it broad, and on their outer sides covering the 

 attachment of two small obovate palettes. These palettes are a little 

 oblique, narrower than their length, rounded at their posterior margin, 

 and striated distinctly. Outside these, and much higher up on the 

 sides, are a pair of broader notches, which give origin to a pair of 

 small palettes, ovate and not broader at their ends, and striated 

 obliquely ; and above the insertion of these are a pair of broad, flat 

 spines on the surface of the tail-joint. 



u The body segments are transverse, the axis not much distinguished 

 from the short, pointed, recurved pleura, with a narrow articular 

 furrow, and strongly punctate on the exposed portions. The puncta- 

 tions (in the hinder segments only) are overhung by short plications : 

 such punctations are observable in many Isopod Crustaceans. 



" Locality. — Coal measures of the Joggins, Nova Scotia, in a plant- 

 bed in the middle of the scries. 



u Having looked in vain for a similar pygidium among the large- 

 tailed Isopods, and consulted Mr Spence Bate with a like result, he 



