344 Prof. T. R. Jones and Dr. li. B. IIoll -.'^ tlie 



cataloguing them. Their study and determination were, how- 

 ever, put aside for awhile ,• and ultimately Mr. Vine requested 

 one of us to take the collection in hand for special treatment, 

 liberally offering the whole for acceptance. The work of 

 examining, comparing, describing, and illustrating this exten- 

 sive and excellent series of Upper-Silurian Ostracoda, the 

 more valuable on account of the known horizon of the bed 

 from which each individual has been obtained, was under- 

 taken with pleasure, but has necessarily occupied much time. 



The coincident opportunity of critically examining another 

 large and well-preserved series of Upper- Silurian Entomo- 

 straca was afforded by Mr. John Smith, of Kilwinning, 

 kindly submitting for our determination and description the 

 collection he had formed in 1880, and of which a provisional 

 list was given by one of us in the ' Geological Magazine,' 

 1881, he. cit. 



Among the forms collected, as mentioned above, are the 

 following genera : — Beyrichia, Kirkhya^ Frimitia^ Thlipsura^ 

 JEchmina^ Cytherella^ CytherelUna, Macrocypris^ and others ; 

 but on this occasion we can take only the Beyrichice into 

 consideration. 



With regard to Mr. Vine's collection, he informs us that 

 the same numbers are connected with these specimens, to indi- 

 cate the beds from which they came, as those used in his 

 "Notes on Polyzoa " &c. (Quart. Journ. Geol. Soc. loc. cit.), 

 and that he has found it " quite possible to speak of the rela- 

 tive abundance or the paucity of species m the different 

 washings. From the five ' Buildwas ' localities those marked 

 no. 22 and no. 37 have yielded the greatest abundance of 

 individuals ; nos. 36 and 38, the richest beds for Polyzoa, 

 have been very poor in their yield of Ostracoda. The Coal- 

 brook-Dale washing (no. 43) is likewise poor. In the Tick wood 

 beds, especially no. 25, and in Mr. Young's washing, no. 25*, 

 the Ostracoda are abundant both in species and in individuals ; 

 and the same remark will apply to the ' Shales over the 

 Wenlock Limestone,^ no. 46." 



The order of the beds and the numbers of the boxes of 

 washed material, as adopted by Davidson and Vine, are : — 



" Shales over the Wenlock Limestone, 24 and 46. 



"The Wenlock Limestone, not examined. 



"Upper Wenlock Shales, 25, 25^, 41, 42. Tickwood 

 beds. 



" Middle Wenlock Shales, 43. Coalbrook-Dale beds. 



" Lower Wenlock Shales, 22, 36, 37, 38, 40. Buildwas 

 beds." 



Mr. Vine has already drawn attention to the fact that much 



