Dr. Ivor Thomas — Trilohite Fnuna of Devon and CormcalL 201 



the general outline is semicircular and not parabolic, the cheeks do 

 not show a sudden elevation, the facial sutures have a different course, 

 while the posterior margin of the head-shield is straighter and the 

 marginal border is narrower. 



Compared with Dechenella lialdemanni (Hall) (8, pi. xxi, figs. 7-9 ; 

 7, pi. xxi, figs. 7-9, pi. xxiii, fi.gs. 13-15), from the Hamilton Beds 

 of ISTorth America, D. n.s-s/;^'r« differs, among other respects, in the more 

 gradual tapering of the glabella, in the different course of the facial 

 sutures, the greater breadth compared with the length, tlie greater 

 prominence of the posterior pair of lateral furrows, and differently 

 shaped basal lobes. 



It differs from BecltcneUa ritthergensis, Zimmermann (24, p. 119, 

 pi. i, fig. 4), of which only a part of the head- shield is described, in the 

 longer and slenderer character of the glabella, as well as the different 

 arrangement and jDronnnence of the lateral furrows. 



The glabella of Dechenella romanovshi, Tschernyschew (19, p. 167, 

 pi. i, figs. 4-8), is considerably broader compared with its length than 

 that of our form. 



The only other Dechenella described from British deposits is D. seiosri, 

 Whidborne (22, p. 27, pi. ii, fig. 15). D. ussheri has a broader head- 

 shield relatively to the length, a straighter posterior margin, a slenderer 

 glabella with more prominent posterior lateral furrows, and, finally, 

 different facial sutures. 



Phillipsia mixor, H. Woodward, 18S4. PI. YII, Fig. 11. 



1884. FhilUpsia minor, II. Woodward. A Monogr. of the British Carbouif. 



Trilobites: Paljeontogr. Soc, p. 68, pi. x, figs. 5, 6«, i, 



7, 8fl. 

 1895. ,, ,, H. Woodward, in Ilinde & Fox. *' Ou a well-marked 



Horizou of Radiolariau Rocks ia the Lower Culm 



Measures of Devon, etc. " : Quart. Journ. Geol. Soc, 



vol. li, p. 646, pi. xxviii, fig. 2. 



Descripimi. — A somewhat ahi'3.ded pi/(/ id htm, measures about 4 mm. 

 in length and approximately 4*5 mm. in greatest breadth, and has 

 a general parabolic contour. The rounded and elevated axis tapers 

 fairly rapidly, and reaches a distance of 0'9mm. from the posterior 

 margin. Owing to the abrasion only twelve segments can be seen. 

 The ten prominent lateral pleura are separated from the axial region 

 by a strong furrow, and curve slightly backwards towards the lateral 

 margins, Avliere they bifurcate. The broad marginal border narrows 

 gradually anteriorly, and is ornamented by gi'ooves parallel with the 

 outer margin. 



Locality and Horizon. — This specimen was obtained in the Culm beds 

 of Hestow Farm, near Ideford, Devonshire. 



Remarks. — Phillipsia minor has been described by Dr. Woodward 

 from the Lower Culm of Waddon Barton (23, p. 68, pi. x, figs. 5, 

 6«, h, 7, 8rt), and Hannaford Quarrj-, near Barnstaple (Br?, p. 646, 

 pl. xxviii, fig. 2). 



Phillipsia cf. minor, H. Woodward. PI. Til, Figs. 12, 13. 

 Bescription. — The cephalon is parabolic in contour, and possesses 

 a roughly oval-shaped tumid glabella, with sub-pai'allel lateral borders 



