
1905. | _ the English Species of Nummulites, ete. 301 
as we find by his letter to Professor Jones, he would have been “ very much 
surprised ” a year and a half before to have found correct, de la Harpe pro- 
ceeded to state that the law of the association of species in pairs has 
exceptions. He mentions WV. gizehensis, Vicaryt, obtusa, and says that among 
species with small central chambers (7.e., as we now say, small megalospheres), 
“il est plusieurs dont les homologues n’existent pas ou n’ont pas encore été 
découvertes. Citons anomala, de la Harpe, dubia, de la Harpe, et subplanu- 
lata, Hantk.” Perhaps other species, he adds elsewhere, will be found 
“privées d’une sceur.” 
It is true that in the case of WV. Vicaryi and obtusa de la Harpe did not 
speak from his own observation. They are only cited from Medlicott and 
Blanford’s ‘Manual of the Geology of India’ (published in 1879), and there 
is no evidence that either the collectors or describers of these species were 
looking out for associated forms. So that these cases go for very little. 
Moreover, in the second part of the work, being an “Etude détaillée des 
Nummulites du groupe de la NW. gizehensis Ehrenb.,’ de la Harpe points out 
that this species forms no exception, NV. curvispirus (a form which he had 
previously regarded as identical with WN. Lucasanus) being its habitual com- 
panion, associated with it as he elsewhere (7) says, by thousands and millions. 
But before leaving de la Harpe, let us hasten to call to mind that in the 
fourth part of the ‘ Etude’ (consisting of a systematic account of the group of 
N. Murchisoni, a division of the “Nummulites a filets non reticulés”) and 
published after the untimely death (in February, 1882) of this talented 
paleontologist he departs from the classification proposed in the first part and 
deals with the species in pairs, describing in each case a megalospheric form 
immediately after its microspheric “homologue.” There is thus some ground 
for thinking that in the last year of his life de la Harpe returned to the 
sounder view of the general prevalence of the law of association in pairs which 
he had himself done so much to substantiate.* 
| Although fully convinced of the truth of the doctrine of the dimorphism 
of the species not only of Nummulites, but of mostt of the higher groups of 
the foraminifera, I have often felt, and especially before looking into de la 
* Since writing this I have found the following passage in a paper read by de la Harpe 
before the Société Vaudoise des Sciences Naturelles on September 9, 1881 :—(8, p. 437) 
“Est ce” (2.¢., the law of association by pairs) “une régle sans exception ? Oui, nous le 
croyons. HAatons-nous d’ajouter que ce n’est que tout derniérement que nous avons acquis 
cette conviction.” He proceeds to withdraw the case of Vummulites gizehensis, as in the 
second part of the ‘Etude.’ No mention is made in this communication of the other 
exceptions insisted on in the ‘ Etude.’ 
+ I say most in view of the peculiar character of the pelagic foraminifera, a sr oup on 
which I hope shortly to have something to say. 
