400 Prof. T. R. Jones on the 



limited circulation, and is therefore reproduced here for com- 

 parison. It occurs in the Upper-Silurian mudstone of Deer- 

 hope (?), in the Pentland Hills, as minute casts and impres- 

 sions, often squeezed and closely resembling those of Beyrichia 

 impendens in the same strata. E. impendens has suboval 

 or nearly semicircular valves, with a definite dorsal sulcus, 

 the umbilical end of which has its edges slightly raised 

 and thickened; but this slight elevation of the rim of the 

 furrow may be obsolete or quite absent. This little Entomis 

 is not far removed from E. reniformis (p. 396) in its general 

 character. Size ^-^ X j\ inch. 



9. Bolbozoe scotica, sp. nov. (PI. XV. figs. 15-17.) 



The genus Bolbozoe was instituted by M. J. Barrande in 

 1868, and described in detail in 1872 (Syst. Silur. Boheme, 

 vol. i. Suppl. p. 502). It contains several forms nearly re- 

 lated to Entomis, but having the anterior moiety of the valve 

 raised into a definite, isolated, round tubercle, varying in 

 relative size in different species. The dorsal sulcus of En- 

 tomis may be said to be here devoted to the formation of the 

 posterior and concentric boundary of the relatively great 

 tubercle of the bulbous anterior part of the valve. 



Bolbozoe anomala, B. bohemica, and B. Jonesi are the Bohe- 

 mian species, all Upper Silurian. The first {op. cit. p. 501, 

 pi. xxiv. figs. 27-30) is almost matched by my " Entomidella 

 divisa]''' but in the latter the shape is more acutely ovate, 

 and the tubercle is relatively larger ; it must, however, be rele- 

 o-ated to Bolbozoe. B. Jonesi belongs also to this division. For 

 B. bohemica {ibid. p. 502, pi. xxvii. figs. 14-20) we have a most 

 interesting analogue in some specimens from the Upper- 

 Silurian mudstone of the Pentland Hills. M. Barrande 

 o-ives figures of seven stages of his species here mentioned 

 (from his Etage E e 2) ; and we can otfer drawings of three 

 apparently distinct stages of growth of our Scotch species. 

 In this, as represented by internal casts, the anterior bulb or 

 tubercle is not nearly so large as in B. bohemica, but the oblique 

 shallow furrows on the hinder moiety of the valves*, charac- 

 teristic of the latter species and making a second division of 

 the genus, are present (figs. 15-17). 



B. scotica remains to us as small internal casts, ovate, 

 broad anteriorly and narrow behind, with a tubercle in front, 



* This character was represented in Mr. G, C. Haswell's published 

 sketch of what I afterwards called Cpprosis HaswelJii (Geol. Mag. dec. 2, 

 vol. -viii. 1881, p. 338, pi. ix. figs. 6 o, 6 b), and M. Barrande was thereby 

 led to regard it as being probably a Bolbozoe {pp. cit. p. 501) ; but the 

 Cypiidinai notch removes it from this group. 



