8 TEST ACE A ATLANTIC A. 



is even stronger still, two species only, the H. lancerottensis 

 and lenticula, having been ascertained to be positively universal), 

 surely some explanation is required for a fact so unprecedented 

 and remarkable. 



If it should be urged however that the smallness of the 

 three Desertas renders it so unlikely that any large number of 

 species would be found upon each one of them separately that 

 the parallel drawn between the 5 Madeiran and the 9 Azorean 

 islands is hardly a just one, I will regard the Desertas as consti- 

 tuting a single detachment of the archipelago. But even in that 

 case the species which have proved hitherto to permeate the 

 entire group (composed of Madeira proper, the Desertas, and 

 Porto Santo) are but 8 in number, out of the 176, which it 

 will be admitted form a striking contrast to the 23 (out of a 

 fauna of only 69) which have been placed on record by Morelet 

 and Drouet as existing on every one of the nine islands of the 

 Azorean cluster. 



As in the other local catalogues, I have appended an asterisk 

 (*) to those few species which have been observed also in a sub- 

 fossilized state ; and in those instances where they have been 

 found only subfossilized, under which circumstances they must 

 be looked upon as extinct (at any rate until further evidence shall 

 have proved the contrary), the names have been put likewise in 

 italics. 



In accordance with the remark which I have just had occa- 

 sion to make, the capitals which precede the exceptionally wide 

 habitats given in the Azorean list at the close of the present 

 section indicate the authorities which must be held responsible 

 for their accuracy, the letter ' M ' referring to M. Morelet, and 

 4 D ' to M. Drouet. 



Sectio I. INOPERCULATA. 



Tam.1. LIMACID^E. 

 Genus 1. ARION, Ferussac. 



Arion ater. 



Limax ater, Linn., Syst. Nat. (ed. 12) 1081 (1767) 

 Arion empiricorum, Fer., Tabl. Syst. 17 (1821) 

 ater, Lowe, Proc. Zool. Soc. Lond. 162 (1854) 

 empiricorum, Alb., Mai. Mad. 11 (1854) 

 rufus, Morel., Hist. Nat. des Acor. 137 (1860) 

 Drouet, Faun. Acor. 140 (1861) 

 ater, Paiva, Mon. Moll. Mad. 2 (1867) 



