402 Prof. T. R. Jones on the 



Renter's above-mentioned variety of his B. Bolliana (Zeitschr. 

 deutscli. geol. Ges. vol. xxxvii. 1885, p. 646, pi. xxvi. fig. 21), 

 although it has a finely granulated surface. I do not agree 

 with Hr. Renter's synonymy for this form (Silur. Ostrac. 

 Gothland, 1887, p. 3). 



The ventral margin differs in development with individuals. 

 Two were sent to me by Prof. Lindstrom in 1886 from Frojel. 



7. Beyrichia tuherculata (Kloden) and varr. 

 (PL XXI. figs. 12-17.) 



For B. tuherculata (Kloden) see Ann. & Mag. Nat. Hist, 

 ser. 5, vol. xvii. p. 347, pi. v. figs. 4-9 (figs. 10-11, var. 

 nuda^ is the same as B. Kochii^ Boll). See also op. cit. 

 April 1886, pp. 347-349, for synonyms, correcting as above. 



7*. Beyrichia tuherculata, vera (senex). 

 (PL XXI. tig. 12.) 



In PL XXI. fig. 12 we have what I believe to be an old 

 individual well developed, but unfortunately broken at its 

 antero-dorsal region, where the middle lobe and the dorsal 

 portion of the front lobe have been displaced inwards by 

 pressure. Kloden's fig. 22 comes nearest among published 

 figures to this specimen ; but the lobes are more divided and 

 the hinder lobe more distinctly sulcate in that figure, and our 

 specimen is denticulate on the front margin and has a few 

 prickles behind. Boll's fig. 1 a of B. tuherculata has the 

 lobes still more distinct ; the hinder lobe exhibits its three 

 characteristic segments ; the front lobe is distorted by hyper- 

 trophy ; and the margin is broad and somewhat tuberculate 

 in front. The Nova-Scotian specimen (Geol. Mag. 1881, 

 pi. X. fig. 10) is another of these full-grown and coarse- 

 featured individuals, retaining the essential characters, how- 

 ever much modified they may be by age. 



7**. Beyrichia tuherculata, var. spicata, nov. 

 (PL XXI. figs. 13, 14.) 



Diff'ering, it may be, by advanced growth only, fig. 13 

 shows isolated spikes or prickles on its lobes and sharp teeth 

 both along the front border and on what remains of the hind 

 margin. The lobes are distinct ; the anterior lobe is modi- 

 fied by an enlargement of its lower moiety; the posterior 

 lobe is broken, but shows some signs of its normal sulcation, 

 and has a projection on its dorsal edge as in fig. 12. 



