106 Messrs. W. K. Parker and T. R. Jones on the 



pherical margin. These indicate altogether nearly fifty chambers 

 in the outer whorl, the lateral lobes of which, in passing towards 

 the umbonal centre, interfere with each other, leaving only indi- 

 cations of half as many elongate triangular sinuous umbilical 

 lobes. 



In the section, fig. c, we see four whorls and a round central 

 primordial cell ; and the outer whorl has seventeen chambers, 

 narrow from back to front, transversely wide, and obliquely set. 



13. Nautilus venosus. Page 59, pi. 8. figs. e-h. " Recent : 

 Red Sea." From shell-sand sent by Spengler. 



A small, smooth, lenticular Nummulina (1 line in diameter), 

 marked with twelve translucent, sinuous, radiating septal lines, 

 several of which appear to bifurcate, and some to trifurcate, at 

 their peripheral extremities. These may indicate seventeen 

 chambers of irregular width, the umbilical lobes of which inter- 

 fere with each other, leaving only about twelve broad triangular 

 lobes on the surface, with small intercalations. In the section, 

 fig. g, three and a half whorls and a central cell are seen ; the 

 outer whorl is here figured as made up of twelve rhombical 

 chambers. 



The only difference between Nummulina venosa and N. radiata 

 is that in the latter the chambers are relatively larger (twice the 

 size), the segments of sarcode produced at each gemmation 

 having been thicker from back to front than in the former shell. 

 The angle at which the segments are set on is the same in the 

 two shells, and the lobes or flaps laid on the umbilical surfaces 

 have in both the same gentle sinuous form, though in one shell 

 they are of half the size that they are in the other. As the 

 relative size of the segments cannot be accepted as a specific 

 distinction, we do not regard these two Nummulince as belonging 

 to separate species. Fichtel and Moll themselves had some 

 hesitation in giving them two names. 



In Prof. Williamson's Nummulina jjlanulata, Monogr. p. 37, 

 pi. 3. figs. 7Q, 77, we have a similar little shell (yV ~tg "^^^^ ^"^ 

 diameter), with straight or rather wavy radii : the umbilical 

 area is left open by the shortened apices of the lateral lobes, so 

 that parts of the former whorls are visible, — a condition retro- 

 spective of some Operculina. Prof. Williamson had his speci- 

 mens from Portsmouth and Scarborough ; and he refers it cor- 

 rectly to the A^. planulata of Lamarck, more especially to the 

 biconvex variety known as A^. vuriolaria, Lam. We have no 

 doubt of this belonging to the same species as the two varieties 

 above mentioned, although the curvature of the septal lines is 

 modified in some of the later chambers, and though there is an 

 umbilical deficiency of shell matter. From Ilund Island, in 

 Davis Strait, we have some small, delicate, recent Nummulince 



