354 Prof. T. R. Jones — On some Palceozoic Phyllopoda. 



Ft. Bohemica, Barrande, Syst. Sil. Bolieme, vol. i. Suppl. p. 464, pi. 

 25, figs. 25, 26. From the Etage D (Lower Silurian) of Bohemia. 



IX. — Crescentilla, Barrande, 1872. 



This is represented by very minute, smooth, subconvex, bicres- 

 centric tests, that is, consisting of two nearly semicircular or short- 

 reniform laterals, with symmetrical hornlike points or angles pro- 

 jecting outwards from the front and hind quarters. The dorsal joint 

 or suture occupies only a small portion, owing to the convexity of 

 the inner edges of the two wings ; and the front notch is occupied 

 by the usual small, triangular, cephalic piece. At least this 

 impression is conveyed by the figure la (pi. 26, op. cit.) given by 

 Barrande when looked at upside-down. 



This curious little fossil occurs in varying numbers throughout the 

 " quartzites D, d2, d3, d4, and d5," of Bohemia. 



X. — Apttchopsis, Barrande, 1872. 



Syst. Sil. Boheme, vol. i., Suppl. p. 436, p. 455 ; and H. Woodward, 

 Geol. Mag. Vol. IX. p. 564 ; Keport Brit. Assoc, for 1872, p. 323. 



A circular or elliptical, subconvex, tripartite shield or carapace, 

 divided by a median (dorsal) suture, and by a transverse angular 

 suture in the front third of the shield. A concentric linear ornament, 

 made up of lines of growth, is characteristic, as in Discinocaris, etc. 



1. A. prima, Barrande, 1872. Op. cit. p. 457, pi. 33, figs. 1-21. 

 These comprise a long obovate form, and a less number of short 

 round shields. These latter we propose to recognize as a variety, 

 and name it var. secunda, because M. Barrande years ago used 

 to label the round forms as " Aptychiis secimdus," before he had 

 determined its Crustacean relationship, and separated it from the 

 more numerous and evidently allied form. They are from the 

 limestone and shales, respectively, of Etage E, e 1 of Butowitz, Borek, 

 etc., in Bohemia. 



2. A. Wilsoni, H. W., 1872. Geol. Mag. Vol. IX. 1872, p. 565, and 

 the Sixth Eeporton Fossil Crustacea, Brit. Assoc. Rep. for 1872, p. 323. 



A large round form, from the Eiccarton beds. Upper Silurian, near 

 Hawick, Scotland. 



3. A. Lapworthi, H. W., 1872. Locc. citt. 



A neat obovate tripartite shield (when complete). Sometimes 

 retaining all three pieces in place. From the Moffat Shales of the 

 Birkhill Group (Lower Silurian), Selkirkshire. 



4. A. glabra, H, W., 1872. Locc. citt. 



A round shield, smaller than A. Wilsoni, and different in outline 

 from both that species and Apt. prima, var. secunda. From the Gala 

 beds (Upper Silurian) of the Moffat district. 



5. AptycJiopsis, sp. nov. 



In the British Museum is a lateral piece of an AptycJiopsis, delicately 

 ornamented, and shaped differently from the others. Unfortunately 

 it has no locality noted. 



6. AptycJiopsis, sp. nov. 



In the Museum of Practical Geology several specimens of lateral 

 pieces, in different stages of preservation, from the Tremadoc Slates 



