60 Description of Genera and Species. 



Paljemysis tenuis sp. nov. PL VIII., figs. 20-24. 



Specific Characters. — Smaller, more delicate form, with relatively less taper in tail 

 and with less difference between the length of the uropods and the deeply-forked 

 telson than in the type species P. dunlopi. 



General Description. — This name is proposed for a small form the tails of which 

 occur in great profusion in certain layers of the " Scorpion-bed " exposed in the Eiver 

 Esk, Glencartholm, near Langholm. The integuments are so thin and delicate that the 

 fossils can only be seen when the slabs are held in a certain light, hence the name. 

 FifTures drawn natural size show the nature of these tails and the relative proportions of 

 their parts; only in one case, fig. 23, has anything approaching what might be construed 

 as a trunk organ been seen. In that figure, what is probably a very short carapace 

 is seen doubled together, and the remains of what may have been one of the limbs. 

 As can be seen, there is a difference in the proportion of some of the forms, some being 

 much more slender than others, but this may only indicate sex. They all agree in 

 having the sixth tail segment more elongated than the rest, in having a very short 

 forked telson with a marked median line, whether ridge or depression is not certain, 

 and terminating in accessory swimmerets. The external branch of the uropods is long 

 and blade-shaped, and the inner branch short, weak, and Unguate. Fig. 24 shows one 

 of the specimens enlarged. Fig. 15 is drawn from a recent My sis from Granton, for 

 comparison. 



Loccdity. — Glencartholm, Langholm, Dumfriesshire. 



Horizon. — Calciferous Sandstone Series. 



Collector. — A. Macconochie. 



Pal^emysis sp. PI. VIII. , fig. 25. 



Yet another portion of a tail evidently belonging to species of this group occurs 

 in the collection made by Mr. Macconochie from the Langholm Scorpion-bed. It is 

 shown in fig. 25, natural size. 



Family EUPHAUSIID^. 



In the collection of the Geological Survey of Scotland there are a great many 

 specimens of fossil Crustacea from the Carboniferous Rocks which must be placed witliin 

 this family. In these forms all the legs are distinctly developed as in the modern genus 

 Bentheuphausia of G. 0. Sars. 



