26 Transactions of the Society. 



sea-coasts, but tliat the European coasts are poor in species and that 

 they are very small, the sole exception being the Adriatic Sea, where 

 the species are more varied, and of greater size. The inaccuracy 

 of this observation is made clear below (see pp. 32, 44, 52, 56). He 

 then goes into the question of the geological distribution of the fossil 

 forms, showing that he had paid far more attention to these than 

 to the living forms which swarm upon the shores adjacent to La 

 Eochelle. He observes (p. 247) that until now only 100 species at 

 most were well known,^ adding, " we have greatly augmented the 

 number, since I present (in this work) between six and seven hundred 

 very distinct species." He was much interested in their methods 

 of growth, on the plans of which he erroneously founded his six 

 Families, which I may as well set out once and for all in this 

 place.^ 



I. Monostegues (fiova, siru/le ; aTeyr], chamber). 

 II. Stichostegues {arlxo^, row). 



III. Helicostegues (eX,t|, spiral). 



IV. Entomostegues {evrofia, cut up). 



V. Enallostegues (evc\\o<i, alternating). 

 VI. Agathistegues (dyadU, a hall of thread). 



The First Family Monostegues made its first appearance in 

 the Cuba Memoir. In 1852, in the " Cours Elementaire " (Bibl. 

 XIV.) he added a new Family, called Cyclostegues {KVK\6<i, circle), 

 for which see Appendix F. (note 31). 



This classification was merely a system based upon the super- 

 ficial appearances of the shells, and was not destined to outlive its 

 author, excepting for purposes of taxonomy, though, as Fischer 

 observed in 1878,^ some systematists adhered to it still. As soon 

 as the internal structure of the tests came to be studied the whole 

 edifice fell to the ground. To this matter I shall return later on, 

 when dealing with Carpenter's criticisms of d'Orbigny and his 

 system. 



Such, then, are the circumstances and conclusions which led 

 up to the " Tableau Methodique," to the contents and composition 

 of which we may now address ourselves. 



D'Orbigny's estimate of the number of species described in the 



1 It will be remembered that d'Orbigny pere wrote to Fleuriau de Bellevue 

 that his son was engaged (in 1819) in drawing "over a hundred species and 

 varieties from the Anse de rAiguillou and Angoulins." 



- He noted the presence of a primordial chamber in all cases (he had not j'et 

 recognized or included any naonothalamous forms — see p. 52), and the manner in 

 which the succeeding chambers become added to it, always an entire chamber at a 

 time, and remarks, " Often the added chamber is as large in itself as the whole of 

 the rest of the shell, a circumstance which must occasion very great displace- 

 ments in certain parts of the animal" (I., p. 247). 



* XXI., pp. 435-6. 



