lOO G. F. MATTHEW ON THE 



RETIOGRAPTUS, Hall. 



Retiograptus tentacxjlatus, Hall ? 



ScliograpUm teniacvlatus, Hall, Can. Org. Kem. Dec. ii., p. 116, PI. xiv., figs. 6 — 8. 



Some few specimeus, not sufficiently well preserved to make the identification sure, 

 are found in the layers of slate (Sd) with the other graptolites. They show two rows of 

 cross-lines, apparently representing the cell partitions. 



BR1CHIOPOD4. 



In this division of the St. John Group the articulate brachiopods are present in much 

 greater numbers and variety of species than in the older part of the formation ; especially 

 we notice the presence of species of Orthis wherever the conditions were favourable to 

 their preservation ; sometimes in immense numbers, but the leaching action which these 

 sediments have undergone, leaves often but a thin film of calcite (and that frequently 

 distorted by dynamical movement in the shale), flattened and featureless, to represent a 

 once distinct brachiopod. The genera Camerella and Strophomena now show themselves 

 in the Cambrian faunas of the Atlantic coast. 



ORTHIS, Dalman. 

 Orthis Electra, Bill., var. major, n. var. (PI. YIL, figs. 3a — c.) 



Nat. Hist. Soc. of N.B., Bulletin x., p- vii. 



This variety is nearly one-half longer than the type, and proportionately wider. It 

 has from 50 to 70 fine radiating ribs, which sometimes are sharp and sometimes rounded 

 on the summit ; when sharp the furrows between are rounded and show numerous faint 

 transverse striulas. The umbo of the ventral valve is quite low, and that of the dorsal 

 appressed to the hinge line. A mould of the beak of the ventral valve, shows that the 

 umbonal depression in the interior is small, being only about two-sevenths of the length 

 of the shell ; the depression is of an oval form, slightly trilobed in front, and bounded by 

 a distinct ridsre. A mould of the interior of the dorsal valve shows it to have a low ob- 

 tuse ridge along the median line, from the deltidium for half of the shell forward, where 

 it becomes obsolete ; this ridge has near the front on each side, a pair of faint diverging 

 furrows ; and on each side near the hinge, a higher and sharper curving ridge, outlining 

 a depression in this valve similar to, but smaller than that of the ventral valve. 



Size. Length 9J mm., width 13 mm., length of hinge 8 mm., height of area of 

 ventral valve 1 mm. 



Horizon and Localiiy. Found in calciferous sandy (or siliceous) nodules in the black 

 slates of Div. 3rf at the Suspension Bridge. 



var. L.^VIS, n. var. 



This variety is comparatively smooth, having more distant, low, thread-like ribs 

 about 30 in number. The cardinal angles are depressed. 

 Size, Horizon and locality as the preceding. 



