332 Prof. T. R. Jones on 
EXPLANATION OF PLATE XVIII. 
Figs. 1-7. Structure of cuticle in the different species. 
(Object-glass } inch.) 
Fig. 1. Gordius fasciatus, Baird. 
Fig. 2. Gordius fulgur, Baird. 
Fug. 3. Gordius subbifurcus, Meissner. 
Fig. 4. Gordius verrucosus, Baird. 
Fig. 5. Gordius gratianopolensis, Charv. 
Fig. 6. Gordius diblastus, n. sp. 
fig. 7. Gordius pachydermus, n. sp. 
XXXIII.—WNotes on the Paleozoic Bivalved Entomostraca. 
No. XII. Some Cambrian and Silurian Leperditie and 
Primitie *. By Prof. T. Rupert Jonss, F.R.S., F.G.S. 
[Plates XIX. & XX.] 
SINCE the publication of my notes on Scandinavian, British, 
and North-American Leperditie, in the Ann. & Mag. Nat. 
Hist. ser. 2, vol. xvii. pp. 81-100, ser. 3, vol. i. pp. 244-257, 
and pp. 840-342 (1856-58), considerable additions have been 
made to the list of known species, and to some extent a re- 
vision of the members of the group has been carried out. 
M. Fr. Schmidtt has given a careful monograph of the 
Leperditie of Russia and neighbouring countries; and Dr. 
Lars Kolmodin{ has similarly treated those of his own 
country. 
My esteemed friend M. J. Barrande has given us in his 
admirable ‘Systéme Silurien du Centre de la Bohéme’§, a 
perfect bibliographic history, as well of this genus as of some 
closely allied genera, as far as the date of his publication 
reaches; and, besides the descriptive details of the generic 
characters and an account of the new species discovered by 
himself in Bohemia, he has elaborated several most useful 
tables showing the geographical and geological range of the 
known forms of Leperditia, Isochilina, Primitia, and Bey- 
richia. 
* For No. XI, see Ann. & Mag. Nat. Hist. ser. 4, 1875, vol. xv. p. 52. 
+ “Ueber die russischen silurischen Leperditien,’ &c., Mém. Acad. 
Imp. Sc. St. Pétersbourg, sér. 7, vol. xxi. (1878). 
{ ‘ Bidrag till Kannedomen om Sveriges Siluriska Ostracoder,’ Upsala, 
1869; and “Ostracoda Silurica Gotlandiz,” &c., Cifvers. Kongl. Vet.- 
Akad. Forhandl. 1879, no. 9 (Stockholm, 1880). 
§ le partie: Recherches paléontologiques. Supplément au vol. i. Tri- 
lobites, Crustacés divers, et Poissons. 4to, Paris and Prague, 1872. 
