ON THE FOSSIL PHYLLOrODA OK THE PAL.KO/OIC llOCKS. 



0< 



ends. The edgo-viow of the cast is like a half-opened bivalve carapace, 

 Avitli a definite Ktroiif^ anterior notch and a small weak posterior indenta- 

 tion between the ends of the valves. 



Gijtheropsl'^ is . >t a t^ood jreneric terra; but we cannot offer any 

 additional information on this peculiar form. 



Zonozoe covaplrxa. and Z. Jh'uhon'eitxin (np. cit. p. 554, &c.) iiiay 

 jiossibly prove to be syinmetrical operculii of some shells. 



M. Barrandc's Cnjptocarin ( ap. ril. pp. 460, &c.) was )ilaced by him 

 next to Apti/c/iopsia with considerable doubt. Wo incline to the belief 

 Ihat most of the examples of this little form con-espond with oporcula of 

 Gasteropods, and thus are comparable with such fossils as I'dtariov, 

 which is now known to be the opereulo of a Nerit(ipsi>t. Wo may suggest 

 also that some of tho forms referred to Cri/pttii-nrin have a distant like- 

 ness to tho opercula of such Corals as (I'diLuqiln/llinu, &c. 





IX. Ckescknttlla, Barrrnde, 187:2. Cri:i"-n,itilla pnrjna.r, Barr. ' Syst. Sil. 

 Boheme,' vol. i. Supplem. p. ')07, pi. 20, ligs. la-i. 



Placed among tho doulitful lOntomostracan forms by our late friend 

 Barrande, this curious little fossil seems to us to fall into its natural 

 i;rouping near I'lerocaris and Diptcronin's, for it is open bpJiunl, ar,d, 

 though found in separate parts, it Avas also found with, sides united, and 

 it may have been sutured along the very short line of junction which the 

 shape of its laterals allowod. 



If we look at M. Barrando's fig. 1 h in a position reversed (upside 

 «lown) to that in which it is drawn, we shall readily ob. "ve that the two 

 reniform lateral pieces, meeting at their convex borders, have the charac- 

 teristic triangular cephalic piece at one end, and an open notch at the 

 other, just as in Ptcrocaris. The shape, however, of the nearly semi- 

 <ircular or short-reniform laterals, with their outside crescent points, 

 makes them markedly distinct. The test, apparently smooth, and faintly 

 convex, has been replaced by iron-oxide. It is minute, being only a little 

 more than 1 mm. in fore and alt measurement, by about 2 mm. ac.oss. 

 Specimens were found in Etage d ; some in d 2, near Trubsko ; mosi, in 

 d o, near Trubin : a few in d 4, near Chrustonitz, and d o, near Koenigshof. 



' Thus,' says M. Barrande, ' this species ranges nearly throughout the 

 Quartzites D, c to d of tho Faiinc seivndr.' 



X. Al'TYcnoi'Sis, Barrande, 1872. ' Syst. Sil. Boheme,' vol. i. Suppl. 

 pp. 4;{G, 455; and 11. Woodward, 1872, ' Geol. ^lag.' vol. ix. 

 p. 504 ; • Report Brit. Assoc, for 1872, 187:3,' p. 323. 



A circular or elliptical, slightly convex, tripartite shield or carapace ; 

 divided by a median ' donsal ' suture extending from the posterior margin 

 f "• ,vard to within half, or a third, oi" a fifth, of the length of the test, accord- 

 ing to the shape of the latter, and then meeting the api!X of a symmetrical 

 V-shapod suture, which extends to the front margin at different angles in 

 different species. This angular ('nuchal') suture forms a line of much 

 weaker resistance than the longitudinal suture ; and the carapace has 

 very fiequoutly given way after the death of the animal, and allowed the 

 triangular (' rostra' " or ' cephalic ') ])ortion to bo removed, together with 

 the anterior limbs and soft parts of the animal, as suggested Jby Dr. H. 



