22 Messrs. Parker, Jones, and Brady on the 



Model no. 20. Orbiculina nwnismalis*, Lamk. Page 305, no. 1. 



Hab. The Antilles and the Marianne Isles. PI. I. fig. 21. 



Though he adopts this form as the type of the genus Orbicu- 

 lina, D'Orbigny rightly associates the three forms catalogued by 

 Lamarck as O. wicinata (adult), O. nwnismalis (middle-aged), 

 and 0. angulata (young) as the same species in different stages 

 of growth. O. orbiculus, F. & M., termed O. nummata by La- 

 marck, should also be included amongst the middle-aged forms. 

 Subsequently D'Orbigny took the adult form, with the well- 

 known name " adunca," originally conferred on it by Fichtel 

 and Moll, as the central type ; and we find this figured in the 

 "Cuba" Monograph, pi. 8. figs. 8-16. On the same plate 

 (figs. 4-7) we find another adult form of Orbiculina, thin, flat, 

 and orbicular, with the name of O. comj)ressa. 



Model no. 21. Dendritina Arbuscula*, D'Orb. Page 285, 

 no. 1, pi. 15. figs. 6, 7. 



Hub. Fossil near Bordeaux. PI. I. fig. 20. 



The thick robust variety of Peneroplis pe?'tusus, with a single 

 large aperture running into irregular dendritic ramifications. 

 Found recent in tropical seas. 



Model no. 22. Articulina nitida*, D'Orb. Page 300, no. 1. 



Hab. Fossil near Paris. PI. I. fig. 2. 



An elongated subcylindrical variety of Vertebralina striata, 

 previously figured and described by Batsch as Nautilus conico- 

 articulatus. It is an exceedingly variable form, and may be 

 found in every gradation, from the narrow subcylindrical con- 

 dition represented in the Model to the broad Renulites opercu- 

 laria of Lamarck. The specimens taken from the abyssal depths 

 of the Mediterranean and the deeper portions of the Red Sea 

 are characteristically small. In the Eocene marl of Baljik, in 

 Bulgaria, small and still more elongated specimens occur. 



Model no. 23. Polymorphina Thouini, D'Orb. Page 265, no. 8. 

 Hab. Fossil near Paris. PI. II. fig. 49. 

 A long narrow variety of P. lactea, W. & J. 



Model no. 24. Spirolina cylindracea*, Lamk. Page 286, no. 1. 



Hab. Fossil near Paris. PI. I. fig. 19. 



The crozier-like, deep-water form of Peneroplis pertusus, com- 

 mon in the Grignon Tertiaries, and found recent in the deeper 

 seas of tropical climates. Notwithstanding the identity with 

 Peneroplis, the distinctive name Spirolina is convenient, if not 

 necessary, in separating the long subcylindrical varieties from 

 the outspread forms found in shallow water. 



