752 Transactions of the Society. 



Bentalina vertebralis Batsch, plate XIV. fig. 39a, b. Nautilus 

 (Orthoceras) vertebralis Batsch, 1791, Conchyl. Seesandes, p. 3, 

 No. 6, plate ii. figs. 6 a and b. — Six-sided, with horizontal chambers. 

 Our figure is narrower and longer than that figured in ' Challenger ' 

 Report, plate lxiii. fig. 35. This and a fragment from the black 

 clay. 



Ehabdogonium Reuss [I860]. 



Rhabdogonium tricarinatum (d'Orbigny), plate XV. fig. 1 6a, b. 

 Vaginulina tricarinata d'Orbigny, 1826, Ann. Sci. Nat., vii. 

 p. 258, No. 4 ; modele No. 4. — A many chambered Nodosarine ; 

 the chambers triangular. Balkwill and Wright in Trans. R. I. 

 Acad., 1885, xxviii., plate xii. figs. 17, 18, figure a recent specimen 

 of this variety. In their figure we are only shown a two-chambered 

 form, whilst d'Orbigny 's original has many chambers. Our 

 example agrees with Balkwill and Wright's figure in having two 

 chambers ; but the lower chamber in our specimen is rotundate and 

 not ribbed at the angles ; moreover there is a marked swelling on 

 two sides, and one of the ribs is double. The mouth also differs ; 

 in ours it is stellate,* in theirs it is triangular. These differences, 

 however, we do not consider sufficient to allow us to form a new 

 variety. One specimen ; brown clay. 



Marginulina d'Orbigny [1826]. 



Marginulina bullata Reuss, plate XV. fig. 17. Reuss, 1845-6, 

 Verst. bohm. Kreide, part i. p. 29, plate xiii. figs. 34-8. — A 

 dwarfed and much curved Marginulina glabra d'O. One specimen ; 

 black clay. 



Marginulina Wetherellii Jones, plate XV. fig. 18. Jones, 1854, 

 Morris' Cat. Brit. Foss., 2nd edition, p. 37. — This common and 

 beautiful form shows great variety of sculpture — indeed, so much so, 

 that amongst no more than one hundred individuals we are able to 

 pick out nine or ten different ornamentations. Some of these are 

 smooth, with a transverse rib or limbate thickening at the junction 

 of each chamber; others are like the last, but with scattered 

 tubercles on the chambers ; others with tubercles closely packed on 

 the coiled part of the shell, the upper part having plain limbate 

 sutures or transverse ribs ; a fourth variety, in which the transverse 

 ribs alternate with bands of tubercles ; a fifth has the ribs them- 

 selves broken up into tubercles and irregular bosses, the body of 

 the chambers remaining smooth ; a sixth is tuberculate but with 

 no sutural ribs ; a seventh has the sutural tubercles elongate, and 

 so gradually forming longitudinal ribs ; and lastly, there are speci- 

 mens like our figure, which has its early chambers longitudinally 



* See also Karrer, SB. K. Akad. Wiss. Wien, xliv. (18G1) pi. i. fig. 5. 



