TRIGONTA. 75 



Section 2. — Clavellatj;. 

 Teigonia ingens, Lyceff, 1872. 



1872. Lyceff, p. 24, pi. viii, figs. 1—3. 



1877-9. Ibid., p. 207, pi. xxxvi, figs. 5, G. 



1877. Trigonia Keepingi, Lyceff. Ibid., p. 19(), pi. xxxv, figs. 1, 2. 



Remarhx. — Maas^ states that his T. roelligifnin, from the GauU of Wilhehnshohe, 

 near Langenstein, is related to T. ingens ; but it seems to be clearly distinguished 

 by the greater curvature of the ribs near the carina and the indistinctness or 

 absence of tubercles. 



1\ Keeinngi, Lycett, is known only by the two type specimens from the Spilsby 

 Sandstone. I have carefully compared these with a large series of T. ingens from 

 the Claxby Ironstone — the chief horizon for that species, and find that the 

 curvature and number of the costte and the size of the tubercles vary considerably 

 in different specimens of T. ingens; some forms possessing smaller and more 

 numerous tubercles agree perfectly, in these respects, with T. Keepingi. The 

 plications on the area of the smaller specimen of T. Keepingi are quite similar to 

 those on T. ingens ; but on the larger specimen they are less distinct than usual ; 

 this, I think, is accounted for by imperfect preservation. In comparing the form 

 of the shell in the larger example of T. Keepingi with that of T. ingens it is 

 important to note that that specimen is larger than usual, and that the whole of 

 the marginal parts posterior to the umbo are very imperfect, so that a false idea 

 may at first be taken of the height of the shell. Lycett's figures, although giving 

 a good idea of the character of the shell, are not accurate in either outline or size. 



Types. — T. ingens, from the Carstone of Downham, was formerly in the 

 museum at Lynn, but cannot now be found. Specimens figured on Lycett's plate 

 xxxvi, from the Claxby Ironstone, are in the Museum of Practical Geology ; and 

 also a gutta-percha cast of the original of plate viii, fig. 1. 



T. Keepingi, from the Spilsby Sandstone, in the Woodwardian Museum. 



Disfribution. — Spilsby Sandstone (zone of Bel. lateralis) of Claxby and 

 Donnington. Claxby Ironstone (zone of Bel. lateralis) of BenniAvorth Haven. 

 Carstone of Downham, Norfolk. 



The specimens named T. Keepingi are from the Spilsby Sandstone (zone of 

 Bel. lateralis) of Claxby and Tealby. 



1 'Zeitschr. d. deutsch. geol. Gresellsch.,' vol. xlvii (1895), p. 282, pi. ix, fig. 7. 



