88 PROF, GROOM ON POLYPHYMA LAPWORTHI. [Feb. 1902, 
with a large drawing of ‘Beyrichia’ Angelini, the late Dr. Lindstrom 
informed me that Linnarsson’s original specimen is the only one 
now possessed by the Riksmuseum at Stockholm, and that it is 
well delineated in Linnarsson’s paper. Under these circumstances 
there can be little doubt that the English and Swedish species are 
different. 
V. Diagnosis or PoLyepHymMA LAPWORTHI. 
Shell thin and chitinous; convex, semicircular, with straight 
hinge-line and well-defined angles. Ventral border raised into a 
marginal rim, which narrows posteriorly. Valves, each flat behind, 
furnished with a large, subcentral, obliquely-directed reniform lobe, 
the ventral limb of which is commonly provided with a prominent . 
tubercle; a small, elongated, postero-dorsal submarginal lobe ; two 
antero-dorsal lobes, usually connected with the reniform lobe by a 
low forked ridge: the one hemispherical, the other more anteriorly 
situated, spindle-shaped, directed towards the anterior angle; a 
subtriangular anterior submarginal lobe, and probably a slender 
submarginal posterior ridge. Dorsal margin shghtly raised, and 
sharply bevelled off towards the hinge-line. Valves when closed 
probably not gaping at any point. Prevailing size: about 2 milli- 
metres by 1. 
Horizon.—Lowest Black Shales (Cambrian), Southern Malverns. 
EXPLANATION OF PLATE III. 
Fig. 1. Left valve of Polyphyima Lapworth, gen. et sp. nov. (No. 305.) x22. 
2. Do. (No. 256.) x 144. 
a. Pariot do: CNou2!1.): x 23: 
4.-Do, (No. 141) x 25: 
5. Left valve. (No. 332.) x 22. 
6. Right-valve. (No.177.) xX 21. 
7. Do. (No. 229,) x 17%. 
8. Part of do. (No. 333.) x°‘23. 
\ 
(The numbers in parentheses are those of the original specimens, which are now 
in the Museum of the Birmingham University. | 
