from the Inferior Oolite of the Cotteswolds. 235 



which succeed are directed from the carina obUquely downwards ; 

 they are straight, are regularly and densely serrated, the spaces 

 between the costse forming naiTow deep grooves. 



T. duplicata, Sow., approaches our shell in the general figure 

 and in the arrangement of the costse, but the latter costse of 

 T. duplicata are dichotomous and waved, the serrations being 

 irregular ; neither of these features are observable in our shell. 



It is very rare ; the largest specimen is an inch and a quarter 

 in length upon the marginal carina, and an inch in the opposite 

 direction. I have only seen two specimens. 



Near Nailsworth, in the freestone beds. 



Trigonia tuberculosa, Lycett. PI. XI. fig. 9. 

 Trigonia tuberculosa, Lycett in Ann. & Mag. Nat. Hist. 1850, p. 422. 



Shell small, depressed, ovately trigonal; umbones recurved, 

 anterior and inferior borders rounded, posterior border slightly 

 excavated ; area small, transversely striated, the striations being 

 large and irregular ; marginal and inner carinse narrow, elevated 

 and sti'iated ; the tuberculated costse are numerous (18 in the 

 adult), curved concentrically with veiy densely arranged tuber- 

 cles ; the tubercles are rather depressed, ovate or clavate, their 

 longer diameter directed downwards. 



A pretty little species distinguished from the young of T. 

 striata by the more numerous costce and by the peculiarities of 

 the tubercles. 



It is rare ; for the present example I am indebted to the 

 kindness of the Rev. P. B. Brodie, who has procured several spe- 

 cimens in the shelly freestone of Leckhampton Hill. 



Trigonia clavo-costata, Lycett. PI. XI. fig. 6. 



Trigonia clavo-costata, Lycett in Ann. & Mag. Nat. Hist. 1850, 

 p. 425. 



Shell subtrigonal ; umbones obtuse, not recurved, anterior side 

 produced, its border rounded, posterior border straight, oblique 

 aud truncated ; area flattened, finely striated transversely and 

 tricarinated ; the marginal and median carinse have regular mo- 

 derate-sized tubercles, the inner carina has numerous transverse 

 plications ; the other portion of the surface is ornamented with a 

 few rows of concentric tubercles ; the tubercles are large, about 

 eight in a row, the first two or three, and the latter one or two 

 rows consisting of costae which are not divided into tubercles. 



Compared with Trigonia decorata, it is smaller and shorter pos- 

 teriorly, the area has finer striations, the carinse have larger and 

 more distantly arranged tubercles, the concentric costse have 



