54 STABILITY OF THE (iENERA. 



among themselves like those of the Amphioxus and of Homo 

 sapiens, between which imaginary evolution has worlced, 

 according to theory, in nearly the same period of time. 



But the material facts discovei'ed by pahvontology and 



accessible to everyone, dispel all illusion. In effect, the 



Nautilides, notwithstanding the great number of their 



specific forms, which must exceed 300, depart so little from 



their initial type, throughout the geological ages, that the 



merest novice would not hesitate in any case to recognize 



their generic nature. Tiie variations or ditferences among 



the species, oscillate without any tendency to continue in a 



single direction so as to found a new type. In the actual 



fauna. Nautilus doe's not show, between its forms and the 



primitive forms, any greater differences than those which all 



naturalists agree in considering as purely specific. Even the 



Triassic Nautilides show less affinity to existing species than 



do the primitive forms. The theoretical evolution of the 



cephalopods, like that of the Trilobites, appears to us to be 



imaginary, without any foundation in fact.'*' 



Dr. Paul FiscluM'. in ;i notice of IJarrande's work, whilst 



ncknowU'dging the siri'ugth of thi- facts and ol)servations bi'ought 



foi-ward by tliat distinguislicd pahi-onlologisi against the (k"- 



vclopnieuL Uu'oit. dot-s not consider llicni couchisivc: ••'flic 



type (loniatites, says M. Fisclu'i', lias always been considered l»y 



evolutionists as a natural transition lielween the Xautilus with 



its \-ery simple ])artitions and the roliaceous sutni'es of the 



Ammonite; an opiuion which is st renglhene(l liy the appeai'- 



ance of (Joniatites chi'oiiolooicall.v intermediate between the 



other two. In order to show ihe extreme dilterence which 



exists between the Nautilus and the (ioniaiites. M. Ban-ande 



has studied the chai'acters ol'ihe initial shell in these two genera 



— astuilv which lias ac(|uii-e(l great iin|)ortance since the j)ubli- 



calion of Mr. Alpheiis llyatTs - Fossil ( 'epiialoiioda." 



Mr. Il.vait has shown that the initial clianiher of Naufi/uK 

 Pompih'us shows an elongatiMl ueai'lv lineai' cicatrice, enclosed 

 liy an elliptical snrlace slightly depressed. He supposes that 

 the ovisack was attached to the elliptic surface, and that the 



* " Cephalopodes, Etudes G6nerale8," 224-230, 1877. 



