ON THE FOSSIL PHYLLOPODA OF THE PALEOZOIC EOCKS. 91 



bat it is rather wider than long (oblately circular), and it has a very 

 wide and deep notch. 



4. Aptychopsis glabra, H. "Woodward, 1S72. ' Sixth Report on Fossil 

 Crustacea, Report Brit. Assoc, for 1872,' p. 323 ; ' Geol. Mag.' vol. x. 

 (1872) p. 565. 



This is an almost circular shield when perfect, ' about 7 lines ( , 7 _, 

 inch) in diameter,' with a wide and deep notch, and concentricallv 

 marked. It is like A. Wilsoni in general appearance, but is smaller and 

 different in proportions, having a relatively larger notch. It is also near 

 to the discoidal forms of A. prima, Barrande (var. secunda). It is from 

 the Buckholm beds of the Gala group, Meigle, Galashiels, Dumfries. 

 About 18 mm. in diameter ; nuchal suture sloping at an angle of 50°. 



It may be the same as Gucullelia angulata, Baily, ' Explan. Sheet 135, 

 Geol. Surv. Ireland,' 1860, p. 13, fig. 4 (woodcut). From the Lower 

 Silurian; Cloncannon, co. Tipperary. 



Specimens closely resembling A. glabra have been noticed and figured 

 by Mr. Dairon in the ' Trans. Geol. Soc. Glasgow,' vol. vii. (1883), 

 p. 177, pi. 7, figs. 31 and 34, from the Moffat Shales. 



5. Aptychopsis, sp. 



A single lefthand portion of the shield of an Aptycliopsis in black 

 shale is preserved in the British Museum, unfortunately without locality, 

 which may belong to a distinct species. It has the usual elliptico- 

 triangular shape of these separate moieties, but it is relatively broad in 

 front, with its anterior angle rounded, and the slope of the nuchal suture 

 is at about 35°, which makes a low wide cephalic notch. It has delicate 

 concentric lines, and very delicate radiating rugula? (besides radiate lines 

 due to breakage under pressure). It measured, when perfect, about 27 

 by 25 mm. 



6. Aptychopsis, sp. 



In the Museum of Practical Geology, London, are five specimens of an 

 Aptychopsis, from the Cambrian slaty or schistose strata (known as 

 Tremadoc Slates) at Garth, near Portmadoc, North Wales. They consist 

 of elliptico-triangular moieties of an ohovate Aptychopsis shield in different 

 states of preservation. The apex of the notch is above the centre of the 

 test (unless altered bj pressure), and its slope is at about 50°. The out- 

 line of the whole tripartite shield would be broad-obovate. Concentric lines 

 are faintly marked. The shape was probably (when perfect) broader than 

 the long forms of Barrande's A. prima. It approaches A. Lapivorthi also 

 in outline, but it is not quite so full in the posterior curve, though larger 

 altogether — probably 32 mm. long by 30 mm. broad. 



7. Aptychopsis Salter!, H. Woodward, 1882. 'Geol. Mag.' Dec. 2, 



vol. ix. p. 389, t. 9, fig. 17. 



This distinctly marked species had an ovate outline when perfect, 

 broadest in the hinder half: nuchal suture sloping at about 45°, its apex 

 reaching back a little more than a fourth of the whole length of the test. 

 Length about 35 mm., width 26 mm. 



Upper Silurian (Wenlock Shale), at Pencarreg, Caermarthenshire, 

 South "Wales. 



