ON THE FOSSIL PHTLLOPODA OF THE PALEOZOIC EOCKS. 177 



shining, and filmy valve (or compressed bivalved carapace), seen as an 

 impression and counterpart on a split slab of hard, grey, micaceous mud- 

 stone, which has been subjected to the usual lateral pressure. The valve 

 (3^? xlg^ inch) is acutely subovate, or sharply boat- shaped in outline, 

 convex below and straight above, and was acute probably at each end, 

 though one of them is damaged. It retains a remnant of one of the 

 small, subtriangular, terminal extensions of the dorsal edge, such as are 

 present in L. siliquiformis. See fig. 6 of the annexed woodcuts. 



The surface is peculiarly marked with what seem to be modifications 

 of ornamental strise or linear plaits, namely, very small lenticular and 

 bead-like elevations, which may have resulted from raised longitudinal 

 strise being crossed by the delicate plaiting of lateral pressure at slightly 

 different angles. 



We dedicate this fine species to the memory of our friend, Mr, J. W. 

 Salter, whose labours in elucidating these old Phyllopodous forms are 

 well known. It was found by Dr. R. Roberts in the Tuhwntirbwlch 

 quarry at Portmadoc. 



Another of the old associates of SijmenorAiris in the Tremadoc series 

 is the 'second specimen ' mentioned at p. 220 of our First Report (1883). 

 Though smaller than the foregoing (2!;XiJ? inch), it is of a similar 

 shape, having been acute at both ends (probably, though one is broken), 

 elliptically curved below and nearly straight above, thus having the outline 

 of a sharp-ended boat (fig. 7 of the annexed woodcuts). It is not really 

 ' emarginate ' at one end, as stated at p. 220 of the Report, that appear- 

 ance being due to a slight transverse crack and some inequality of the 

 surface near the end, which was probably acute, but has been squeezed out 

 of shape and frayed away by the longitudinal plaiting of the hard, com- 

 pressed, slaty shale or mudstone. The cross-pressure has also coarsely 

 plaited the valve throughout, and somewhat lengthened it. 



From the upper part of the Lower Lingula-flags, at Caer-y-coed, near 

 Maentwrog. Collected by Mr. D. Homfray. In the Woodwai'dian 

 Museum, Cambridge. 



A somewhat similar, but badly preserved, fossil from the Brethay 

 Flags of Long Sleddale (Marr Coll. in the Cambridge Museum) is 

 probably a hingulocaris of the same, or a closely allied, species. 



3. LiNGULOCARis SILIQUIFORMIS, J. and W. (Woodcuts, Figs. 8 & 9.) 

 ' Geol. Mag.,' 1883, p. 464. 



At p. 228 of the First Report (1883) we described this Cambrian Phyllo- 

 carid as differing from Salter's L. lingulaecomes ' by being longer, sharper 

 at one end, and more nearly resembling a pea-pod in shape. One speci- 

 men (fig. 8 of the annexed woodcuts), rather wrinkled by crush, from the 

 Upper Tremadoc series at Garth Hill, Portmadoc, was presented to the 

 British Museum by the Rev. J. F. Blake. Another (fig. 9), also in the 

 British Museum, is marked '48654 from the Bala Schist at Bwlch-y- 

 gaseg, near Cynwyn, Corwen ; J.P., March 14, 1868.' 



A fragmental specimen from the Upper Tremadoc series at Garth, 

 Portmadoc, is in the Museum of Practical Geology, marked f ; and 

 referred to L. lingulcBcomes at p. 15, ' Catal. Cambr. and Silur. Foss. 

 M. P. G.,' 1878. 



' Besides the two specimens, ^^^ in the Woodwardian Museum (see First Report 

 p. 223), from Garth, there is one in the British Museum, No. 48,001, from the same 

 locality. 



1888. M 



