344 Professor T. Rupert Jones — 



2. Primitia Solvensis, Jones. "Middle Mensevian," or rather higher. Ann. N". H. 



ser. 2, vol. xvii. p. 95, pi. 7, fig. 16 ; ser. 4, vol. ii. p. 55 ; and vol. iii. p. 223. 



3. Leperditia Hicksii, Joues. "Middle Mensevian." Q.J.G.S. xxviii. p. 183, pi. 7, 



fig. 16 (bad). This will be figured again in a forthcoming paper. 



4. Beyrichia EolUi, Jones. " Middle Mensevian." See above.' 



The close alliance of B. intermedia to the last-mentioned may be 

 an illustration of atavism. The re-occurrence of these lower kinds 

 of organisms in Upper Silurian, after the Cambrian and the Lower 

 Silurian, is not strange ; and we know of the re-occurrence of 

 Upper-Silurian Entomostracan species in the Carboniferous strata, — 

 for instance, B. intermedia, as mentioned above, and the apparently 

 Carboniferous species enumerated in the notice of Mr. J. Smith's 

 washings (Geol. Mag. Dec. IL Vol. VIII. p. 75), and known also 

 in Mr. G. R. Vine's collection from Mr. George Maw's washings of 

 the Upper Silurian shales. 



15. Beyrichia tuberculata (Kloeden). Plate X. Figs. 8, 9, 10. 

 Length, \ and \ inch. 



In his papers on the Geology of Arisaig, Nova Scotia, read before the 

 Geol. Soc. Lond.lin 1864 and 1870, the Eev. Prof. D.Honeyman,D.C.L.,^ 

 referred to some Upper-Silurian Entomostraca from that district. 

 At p. 344, Q.J.G.S. vol. xx. they were quoted as Beyricliia pustulosa, 

 Hall ; B. cequilatera, Hall, Beyricliia, 2 spp., and Leperditia sinuata, 

 Hal]. Some specimens from Arisaig left with me by my friend 

 Dr. Honeyman in 1862 for examination were described in the 

 Q. J. G. S. vol. xxvi. p. 492, as being Beyrichia tuberculata (Kloe- 

 den) ; B. WilcJcensiana, Jones ; B. Maccoyiana, Jones ; and Primitia 

 concinna (?), Jones. There are also other Primitice associated with 

 the foregoing. One resembles P. ovata, J, and H. They occur more 

 or less abundantly in a highly fossiliferous dark-gi-ey limestone. 



Fig. 8 is an inside cast of a right valve, devoid of the test ; the 

 main lobe and the postero-dorsal angle are broken. Fig. 9 shows a 

 perfect left valve ; and Fig. 10, a fine right valve, still partly im- 

 bedded in the matrix along the dorsal edge In the latter the anterior 

 lobe is not divided into two as it usually is. 



Probably these specimens may be the same as the form described 

 by Prof. James Hall and Principal Dawson as B. pustidosa, Hall 

 (" Canadian Nat. and Geol." vol. v. p. 158, fig. 19, woodcut; and 

 "Acadian Geol." 2nd edition, p. 608, fig. 216, woodcut) ; but I find 

 no essential difference between the very fine large specimens before 

 me and the Scandinavian specimens of B. tuherculata described and 

 figured in the " Ann. N. Hist." ser. 2, vol. xvi. p. 86, pi. 5, figs. 4-9. 



1 Some other Mensevian fossils have been referred with doubt to Entomostraca, 

 namely, L'pei'difia ? vexata, Hicks. " Lower and Middle Mensevian." I think this 

 to be a portion of a larval Trilobite. Leperditia ? Cambrensis, Hicks. " Red shales 

 of the Longmynd" group. This seems to me to be quite indeterminable at pre- 

 sent. See' Q.J.G.S. xxvii. p. 396, and xxviii. p. 184. 



'^ Fellow of the University of Halifax, Curator of the Provincial Museum, Pro- 

 vincial Geologist, and Professor of Geology to Dalhousie College and University, 

 Halifax, Nova-Scotia. 



