CANARIAN GROUP. 299 



de Conch, v. 345), which had been discovered by himself and 

 M. de la Perraudiere in Teneriffe and Hierro ; and during the 

 following year Mousson contributed four others (Denksch. der 

 Allg. Schweiz. Gesellsch. fur die Naturwiss. xv. 132) from the 

 material which had been collected by Dr. Hartung in Lanzarote 

 and Fuerteventura. 



In 1861 sixteen Helices were published as new (Ann. Nat. 

 Hist., 3rd ser. viii. 104) by Mr. Lowe, the result of his own 

 researches, in conjunction with those of myself, during two ex- 

 peditions to the Canaries (in 1858 and 1859), when we visited, 

 in Mr. Gray's yacht ' the Miranda,' the whole seven islands of 

 the Group ; and in 1864Morelet enunciated four others (Journ. 

 de Conch, xii. 16) as having been found in G-omera. 



It remained yet, however, to elaborate these various contri- 

 butions to the Canarian catalogue into a systematic whole ; and 

 accordingly in 1872 Mousson issued his ' Eevision de la Faune 

 Malacologique des Canaries,' in which he brought together what 

 had previously been published, and embodied the result of cer- 

 tain fresh material which had come to hand, particularly that 

 of M. de Fritsch, a Professor of Geology at Frankfort, who had 

 spent eight months in the archipelago and had visited all the 

 islands. 1 To that of M. de Fritsch was added the material 

 which had been obtained in Teneriffe by Eeiss ; and as Mousson 

 possessed the advantage of a large number of the collections, to 

 which I have just called attention, having been entrusted to 

 him, he was in a position to give a trustworthy resume of what 

 had been done. Although I cannot but think that he has made 

 the species of his Monograph far too numerous, the ' 197 ' re- 

 quiring, according to my estimate, and that too in spite of no 

 less than twenty-one additions with which he was not ac- 

 quainted^ to be reduced by at least eight (in reality perhaps by 

 more), we are nevertheless greatly indebted to him for the 

 careful and conscientious manner in which he applied himself 

 to the difficult task of examining the extensive material (includ- 

 ing a considerable portion of my own) which was placed in his 

 hands ; and if, in the course of the present enumeration, I have 

 occasionally felt compelled to differ from the conclusions at 

 which he arrived, it is in many instances, simply, because, 

 having had fuller opportunities of observation in situ, somewhat 

 greater latitude for the general principle of insular variation has 

 been, to a certain extent, forced upon me. 



1 Mousson says that sept des huit iles principales du groupe ' were 

 explored by de Fritsch ; but he must surely be aware that there are but seven 

 islands altogether which could be described, in any sense, as 'iles principales,' 

 the little rock of Lobos, in the Bocayna strait, having always been cited 

 as a portion of Fuerteventura, and Graciosa, Allegranza, and Clara being 

 mere detachments of Lanzarote. 



