Dr. S. Woochvard — New Palceozoic PhyUopocl Crustaceans. 389 



they might readily be supposed to be the two outspread valves of 

 some Fliolas or Leda-Wke molluscan shell. The carapace, which 

 is 25 mm. in length by 15 mm. in breadth, has an almost wedge- 

 shaped contour, being widest anteriorly. The front of the shield 

 measures 10 mm. across its cephalic portion, represented by the 

 V-shaped cervical sinus, which is also 10 mm. deep. Behind the 

 cervical notch, is a small elliptical area 5 mm. long and 4 mm. broad 

 (reminding one of the lunule of a bivalve shell), having a slightly- 

 raised border; from this area two strongly-marked furrows, com- 

 mencing 1 mm. apart, pass backwards, diverging gradually to 4 mm. 

 distance from each othei*, where they join the posterior border. The 

 space between these two furrows is marked by about 10 delicate 

 raised strias, which diverge slightly like the furrows themselves 

 towards the posterior margin. The lateral portions of the carapace 

 are ornamented with very minute radiating and concentric striae. 



This is the only specimen I have seen from this locality, and I 

 dedicate it with great pleasure to my friend Mr. John Edward Lee, 

 F.S.A., F.G.S., with whom I passed so many agreeable days in the 

 Eifel-district. 



III. Genus Aptychopsls, H. Woodw. 1872. Geol. Mag. Vol. IX. 



p. 564. 

 6. Aptychopsis Salteri, mihi, sp. no v. Plate IX. Fig. 17. 



In my report to the British Association, Brighton, 1872, and in 

 the Geol. Mag. Vol. IX. 1872, p. 564, I gave a notice of several 

 new Phyllopod shields from the Middle Silurian of Hawick, Eox- 

 burghshire, three of which I referred to a new genus Aptychopsis, 

 and named severally A. glabra, A. Lapwortlii, and A. Wilsoni. The 

 last of these is the form which, in jDoint of size, agrees most nearly 

 with the fossil figured in our Plate, Fig. 17, which was obtained by 

 Mr. John E. Lee from the Upper Silurian (Wenlock Shale) of 

 Pencarreg,^ Caermarthenshire. 



This specimen, which exhibits one side of a Phyllopod shield, 

 was marked by the late Mr. J. W. Salter, F.G.S., as the " semi- 

 operculum of a large Orthoceras." Although the operculum of 

 Orthoceras remains unknown, we are now well acquainted with 

 these Phyllopod shields from many localities, and I have every 

 confidence in referring this fossil to the genus Aptychopsis. 



In this specimen the carapace is 35 mm. long, by 25 mm. wide ; 

 the V-shaped cephalic portion is 10 mm. deep, and the posterior 

 dorsal line is 25 mm. long. The surface of the carapace is finely 

 striated concentrically and the lateral border of each valve seems 

 to have the edge bent downwards and to have been slightly con- 

 cave. This is a more oblong form than A. Wilsoni and the angles 

 of the V-shaped cervical suture are sharp in the Welsh specimen, 

 but rounded off in the Scottish example, which is also a more 

 circular form. 



I venture therefore to separate this specimen from Pencarreg 

 specifically from the Roxburgh examples, and have designated it 

 ^ Mr. Lee spells tliis place " Penkerrig " on the label. 



