1 50 Memoirs of the Indian Museum. [Vol. VII, 



appears to have been attempted since the date of their publication, and not only 

 have the three names costatum, fimbriatum and maculatum continued in use as those 

 of distinct species, but the same is the case with some of the other names relegated 

 by Tryon to the synonymy. 



Having had occasion to study a large series of fossil specimens of Dolium from 

 the later Tertiary formations of the Mekran, it became necessary for me to pay 

 special attention to the related recent forms. From a perusal of the published 

 information regarding the recent forms above alluded to, it was not found possible to 

 decide definitely whether certain of the fossils under consideration were to be 

 regarded as identical with some of them or rather to be interpreted as separate 

 varieties or species. In order to establish a trustworthy comparison, it became 

 necessary therefore to undertake a fresh study of the recent forms of which a rich 

 series is preserved in the collections of the Indian Museum. The result of this study 

 has been to confirm some of the identifications established by Tryon, though his final 

 conclusions reach too far in one direction and not far enough in another ; for, on the one 

 hand, there is no difference (not even varietal) between Dolium costatum and D. fim- 

 briatum, both of which represent a single species which should be known as Dolium 

 tessellatum , Bruguière, while, on the other hand, Dolium maculatum represents a 

 totally distinct species. 



The supposed three forms are therefore reduced to two, which, nevertheless, 

 under certain conditions are apt to exhibit a superficially deceptive resemblance to 

 one another. Before discussing their differences and their zoological affinities, it will 

 be useful therefore to give a detailed description of both these forms. 



DESCRIPTIONS. 



Dolium maculatum (Lam.) Deshayes. 



(PL IV, figs. 1-3; pi. V, figs. 4-6.) 



1685-1692. Buccinum sp., M. Lister, Historia Conchyliorum,, pi. 899, fig. 19. 



1757. " Le Minjac," Adanson, Histoire Naturelle du Sénégal, Coquillages, p. 109, pi. vii, 

 fig. 6. 

 ? 1758. Buccinum dolium, Linnaeus, Systema Naturae, Ed. X, p 735. 



1770. Buccinum dolium, Linn. sec. Huddesford, Martini Lister, M.D., Historiœ sive 

 synopsis methodicœ Conchyliorum et tabularum anatomicarum editio altera. 

 pi. 899, fig. 19. 

 ? 1822. Dolium maculatum, Lamarck, Hist. nat. des animaux sans vertèbres, Vol VII, sp. 3, 

 p. 260 

 1831-1837. Dolium maculatum, Lam., Kiener, Iconographie des coquilles vivantes, pi. iii, 

 fig. 4. 

 1845. Dolium maculatum, Lam. sec. Deshayes, An. sans vert., 2nd ed., Vol. X, p. 140. 

 1849. Dolium maculatum, Lam., Reeve, Monograph of the genus Dolium, sp. 4. 

 1857. Dolium maculatum, ham., Küster, Systematisches Conchilien- cabinet von Martini 



und Chemnitz, Vol. Ill, 1st section, 2nd part, p. 73, pi. l.xii, fig. 3. 

 1885. Dolium costatum, Menke, var. maculala, Lam., sec. Tryon, Man. Conch., Vol. VII, 

 p. 264. 



