456 Prof. T. Rupert Jones — On the Palceozoic Phyllopoda. 



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VI. — On Paleozoic Phyllopoda. 

 By Prof. T. Rupert Jones, F.E.S., F.G.S.* 



TNCE the publication of the Third Report on Palaeozoic Phyllopoda 

 (Brit. Assoc. Eeport for 1885), we have examined many- 

 additional specimens in the Museums of the Edinburgh and Glasgow 

 Universities, and in the Braidwood Museum belonging to Dr. J. R. S. 

 Hunter, of Braidwood, near Glasgow. Mr. James Thomson, F.G.S., 

 has given us a quantity of nodules, containing remains of Ceratiocaris, 

 from the Lesmahago district ; and other friends have lent us several 

 interesting specimens. 



We have also again critically examined the fossils enumerated 

 under Ceratiocaris, in the Third Report, and, having had numerous 

 finished drawings carefully made for illustration of a forthcoming 

 monograph for the Palseontographical Society, we have been able to 

 compare them more perfectly and with more precise results. 



Thus we find that — 



1. Ceratiocaris leptodactylus (M-Coy), see Third Rep. pp. 11-14, 

 as known by its caudal appendages (Cambr. Mus. a/223, a/924:, and 

 a few others), is distinct from C. Murchisoni, M'Coy, both as to size 

 and proportions. We have traced two rows of pits (bases of prickles) 

 on a/924, as exposed. Some similar caudal appendages, M.P.G. xi, 

 occur in the Lower Wenlock rock of Helm Knot, Dent, Yorkshire. 



2. C. Murchisoni (Agass.), founded on some specimens figured in 

 Sil. Syst. and Siluria, but unfortunately lost (Third Rep. p. \\ r 

 etc.), is represented by several analogous fossils, such as Oxford Mus. 

 B and C; Ludlow Mus. C; M.P.G. ff and ff. We find only one 

 row of pits on the styles, as exposed. We have been unable to deter- 

 mine its carapace ; but a fragment lying in the same slab with f-f 

 may belong to it. The carapaces formerly assigned to C. leptodactylus 

 and C. Murchisoni (Third Rep. pp. 12, 15) are now regarded as 

 belonging to distinct species. 



3. The caudal appendages of C. Murchisoni have a slight curva- 

 ture ; there are others much like them, but straight, and associated 

 with a large ultimate segment, much broader than that in M.P.G. ff. 

 (For instance, Oxford Mus. F ; M.P.G. X \ ; Ludlow Mus. T.) One 

 of these (X \) has been labelled C. gigas by Mr. Salter ; and there- 

 fore we adopt that name. 



4. The specimens from the Wenlock beds of Dudley and Kirkby 

 Lonsdale, described and figured in the Geol. Mag. 1866, p. 204, 

 PI. X. Figs. 8 and 9, as belonging to C. Murchisoni (Third Rep. 

 p. 12), are too thick and strong for that species, and the Dudley 

 example (Fig. 8) has different proportions. We propose to distinguish 

 them as C. valida. 



5. Some abdominal segments (Oxford Mus. E ; Ludlow Mus. L ; 

 B.M. 39403; M.P.G. ff and ff; Third Rep. p. 20, etc.), narrow in 



1 Being the substance of the Fourth Report of a Committee consisting of Messrs. R. 

 Etheridge, F.R.S., H. Woodward, LL.D., F.R S., and Prof. T. Rupert Jones, 

 F.R.S. {Secretary), on the Fossil Phyllopoda of the Palaeozoic Rocks, read before 

 Section C. British Association, Birmingham, Sept. 8, 1886. 



