Description of Genera and Species. 57 



beyond it, and both were evidently extended beyond tlie telson when the tail fan was 

 not spread out as it is on the specimen. Fig. 8 shows the only specimen known, 

 natural size, which is not compressed. Fig. 9 shows the cast of the counterpart, 

 and fig. 10 is an attempt to restore the parts exhibited in the fossil. 



Remarks. — This species has been named after the Eev. David Landsborough, of 

 Kilmarnock, a keen naturalist, who first brought the specimen to my notice. 



Locality. — Kilmaurs, near Kilmarnock, /Ayrshire. 



Horizon. — Lower Coal Measures. 



Family MYSID.^. 



Remcirl's. — In the collection of the Geological Survey of Scotland there are very 

 numerous specimens of the tails of higher Crustacea, about the systematic position of 

 which there has been considerable difficulty, although the presumption was that they 

 probably belonged to some members of the family Mysidaj. Last year, however, Mr. 

 Tait, collecting under the guidance of Mr. Eobert Dunlop, obtained from the Soft Band 

 Ironstone of Airdrie specimens of tails like those about which there remained a doubt, 

 and in which the auditory organ situated on the inner branch of the uropods is distinctly 

 visible. On the strength of this evidence these tails are now with some degree of 

 confidence assigned to the above family. 



Genus PAL^IMYSIS gen. nov. 



Generic Characters — Integuments chitinous, thin, and smooth. Trunks unkown ; 

 tails long and fusiform, and segments supplied with well-developed epimera and weU- 

 developed pleopods. External branch of uropods much longer than the forked telson ; 

 internal branch of uropods short, so that the tail fan is deeply forked. 



Remarks. — It is almost certain that the above characters are so general that it 

 will yet be found, when better preserved material turns up, that our genus will include 

 the species of several genera. It is, therefore, only proposed provisionally to bring 

 together a group of tails in which there is a great similarity in form and construction. 



Pal.t-:.mysis t)uxlopi sp. nov. PL VIIL, figs. 12-14. 



Specijic Characters. — Tail fusiform, tapering from second segment ; first five 

 segments with well-marked obtusely-pointed epimera ; sixth segment longer and 

 narrower than the rest. Telson shorter than uropods, grooved down the middle line, 

 forked, bearing accessorv swimmerets at the two extremities, and set with a row of 



