488 Dr. S. Woodward — I^ew Carboniferous Trilohites. 



recurrence of the same beds brought in again by faults and folds. 

 The absence of palseontological horizons to fix the position of other 

 beds above and below, is also greatly felt. I have no doubt, how- 

 ever, that if Mr. Pollen is able to give the necessary time to the 

 task, he will unravel the succession, so far as it affects the banks 

 of the Hodder. For larger areas we may look with confidence to 

 Mr. Tiddeman and the officers of the Geological Survey, to whom 

 we already owe so much, for light and guidance. 



Fig. 1. — Pygidium of FkilUpsia Derbiensis, Martin (x 3 times nat. size), in red 



Carboniferous Limestone ; R. Hodder. 

 Fig. 2. — Pygidium of Phillipsia ge^nmuUfera, Phillips, sp. ( x 3 times nat. size), 



in dark grepsh Carboniferous Limestones ; R. Hodder. 



Postscript. — In addition to the numerous remains of Trilohites 

 from the carbonaceous shales of the Hodder bank, Mr. Pollen has 

 sent me up two small pygidia (see Woodcut) obtained by him, 

 Fig. 1 from a dark reddish pebble, Fig. 2 from a dark greyish 

 pebble of crystalline limestone, obtained out of the river-bed itself. 

 As these pebbles have undoubtedly come from points much higher 

 up stream, and have undergone rounding, the exact position of the 

 parent rock is not at present known. 



Fig. 1. — The larger abdominal shield, or pygidium, in the red 

 matrix measures 10 millimetres in length, by 13 mm. broad, and is 

 composed of 13 coalesced segments, very indistinctly seen, being partly 

 decorticated ; the axis of the tail is roundly elevated, about 4 mm. 

 broad at the proximal border, where it articulates with the cephalo- 

 thorax and tapers down to an obtuse point close to the posterior 

 border ; the pleura composing the margin are indicated by distinct 

 lateral furrows on the pygidium, around the mai'gin of which there 

 is a narrow smooth border 1 mm. broad. The surface is not 

 ornamented by any tubercles or punctse. I refer this form to 

 Phillipsia Derbiensis, Martin (see H. Woodward's Mon. Carb. 

 Trilohites: Pal. Soc. Mon. 1883, p. 12, pi. i. figs. 2a, 6, and 9) 

 (see Woodcut, supra, Fig. 1). There is a minute Goniatite imbedded 

 in the same pebble. 



Fig. 2. — The second and smaller tail, preserved in a pebble of 

 glistening crinoidal limestone, is 8 mm. in length and the same 

 in breadth ; it is composed of 14 coalesced segments, the ridge of 

 each segment being ornamented by a single row of very minute 

 tubercles ; there is a very narrow smooth margin around the border 

 of the tail-shield ; the axis is about 3 mm. broad where it articulates 

 ■with the cephalothorax ; it diminishes posteriorly, and it terminates 



