CANARIAN GROUP. 309 



have arrested their progress and caused them to adhere. M. 

 d'Orbigny's diagnosis of the species is as follows : ' Corpore 

 elevato, compresso, griseo-cseruleo, supra rugoso sulcato, pallio 

 oblongo rugoso medio-elevato ; carina elevata secante.' 



According to Mousson, M. Mabille has recently proposed 

 (Rev. Zool. 143; 1868) a new genus, Lallemantia, for this 

 slug, the characters however of which would seem to be in- 

 sufficient. 



Limax noctilucus, 



Limax noctilucus (d'Orb), Fer., Hist. 1 1 . 70. t. 2. f. 8 (181 9) 

 Mouss., Faun. Mai. des Can. 7 



(1872) 



Habitat 6 Teneriffam ' (sec. d'Orb. olim) ; sed species valde 

 dubia. 



It is not without some hesitation that I admit this species 

 into the Canarian catalogue ; because M. d'Orbigny, on whose 

 authority it would seem to have been originally introduced (in 

 1819) into Ferussac's work, makes no allusion to it whatsoever 

 in his subsequent enumeration (in 1839) of the Mollusca of the 

 Canaries. It is highly probable therefore that he had some 

 actual reason for supposing that either the diagnosis or the 

 asserted habitat was inaccurate ; though if this was really the 

 case he ought to have stated plainly what the evidence was on 

 which it was allowed to appear in the ( Histoire Naturelle des 

 Mollusques.' Still, the fact remains that it is both described 

 and admirably figured in the latter magnificent publication, 

 and that nothing has yet been placed on record to call in 

 question its claims to be (as it professes) truly Teneriffan. 

 Yet the complete silence of M. d'Orbigny concerning it in his 

 after-list, and the circumstance that it was established pro- 

 fessedly on a unique example (said to have been taken beneath 

 dead leaves in the mountains of Teneriffe) are points, so far as 

 they go, to cast a decided suspicion on the species, whether as 

 regards its Canarian origin or the truthfulness of its diagnosis. 

 Moreover it is not said by whom the L. noctilucus was cap- 

 tured; for, as it was published in 1819, it clearly could not 

 have been by d'Orbigny himself, whose sojourn in the Cana- 

 rian archipelago did not take place until 1826. 



The great distinctive feature of this slug, a feature which, 

 if true, would certainly entitle it, as Mousson has well observed, 

 to generic separation, consists in the fact of its being sup- 

 posed to possess a mucous disk on the hinder edge of its shield, 

 which has the power of emitting a strong phosphorescent light ; 

 but how far this character is absolutely to be depended upon, it 

 remains yet to be proved. 



