542 Prof. T. R. Jones 8f H. Woodward — Palceozoio Phyllopoda, 



In shape it is obliquely subovate (28mm. long; 13mm. high); 

 broad (high) in front, narrower and rounded behind. The anterior 

 extremity of the valve is boldly rounded in advance of the umbo, 

 but has a slight antero-dorsal slope. The hinge-line is straight 

 (17 mm.) from the umbo to the postero-dorsal curve. The umbo 

 is about a fourth of the length of the valve from the front end. 

 Ventral edge elliptically curved ;' deepest just in front of the middle 

 of the valve. The surface is marked with numerous thin striae, 

 parallel with the ventral margin, and concentric with the umbo. 



This specimen most nearly agrees, as to shape, with Salter's 

 fig. 2, ph X, " Memoirs Geol. Survey," vol. iii (1866), pp. 253 and 

 294; and second edition (1881), p. 485, being more ovate than his 

 fig. 1. Its ornament agrees with that of the latter. The variation 

 in outline may possibly be due to sexual difference. 



4. Cypricardinia (?), Hall, 1859. Plate XV, Figs. 4a, 46. 



This fragment of a molluscan valve, from Girvan, when looked at 

 ■with its broken end downwards, has somewhat of the appearance of 

 a fragmental upper moiety of a Piunocaris, hence it has been figured 

 tentatively in this plate. 



Fig. 4a shows the outside of the posterior moiety of the right 

 valve of probably a Ci/pricardinia, such as C. sublamellosa and 

 C. concentrica, Hall, "Palaeontology of New York," vol. iii, 1859, 

 pp. 267, 268, pi. L, figs. 1 and 2. It measures 9 x 4 mm. Fig. 46 

 gives an enlarged view of a portion of its ornament. 



The specimen is in Mrs. Gray's Collection, in Edinburgh, and 

 was collected by her from the Lower Silurian rocks of Balclatchie, 

 Girvan, Ayrshire. 



5. PiNNOCAKis Lapwokthi, E. Etheridge, jun., 1878. Plate XV, 



Figs. 5-10. 



For descriptions and synonymy see "Monograph Silurian Fossils 

 of Girvan," vol. i, 1880, p. 210, pi. xiv, figs. 17-20 ; and " Monograph 

 British Palgeozoic Phyllocarida," 1892, pp. 118, 119, pi. xv, fig. 24. 



The only known representative of the peculiar Crustacean genus 

 Pinnocaris occurs usually as black, shining, chitinous, flattened 

 carapace-valves (sometimes decomposed) ; elongate and triangularly- 

 obovate in outline ; broadly rounded at one end (anterior) ; with an 

 umbo ; strige parallel to the ventral margin and concentric with the 

 umbo ; and a long, narrow, transversely wrinkled posterior extremity. 



In some instances the valves are subconvex ; and often are 

 evidently in pairs, containing matrix representing animal matter. 

 In no instance have the two valves presented themselves as lying 

 open or expanded side by side. 



The umbo is situated on the straight margin, generally at about 

 a fourth of the length of the valve from the anterior extremity ; but 

 in small specimens relatively at a less distance. It appears typically 

 as a small pinched-up fold, hollow within; but it is much modified 

 by pressure in different individuals; remaining sometimes as a 



