68 Canon A. M. Norman on 



" Colour pale, with two longitudinal brown bands passing 

 down the middle and two other bands on each side ; uropods 

 light red. 



" Length 6 millim., breadth 2*8 millim. 



" The form of the pleotelson and the absence of any true 

 tubercle on the epistome lead us to regard this little species as 

 a Lucasius, notwithstanding that the relative length of the 

 antenna shows more approach to Porcellio (sensu stricto). 

 It differs from Lucanius scitus, B.-L., which is also found at 

 Madeira, in the longer antennae, the greater development of 

 the median frontal lobe, the form of the pleotelson, and the 

 general coloration, which is particularly characteristic." 



The locality in which this species occurred was the Ilheo 

 dos Embarcadouros, the islet at the eastern extremity of 

 Madeira. This rocky islet has a most remarkable vegetation, 

 being the home of a large number of pretty-flowered crassi- 

 folious plants. It is, moreover, the only known locality for 

 three interesting varieties of land-mollusca — Helix erubescens, 

 Lowe, var. advenoides, Paiva, Helix polymorpha, Lowe, var. 

 irrasa, Lowe, and the recently described Helix Watsoni, 

 J. Y. Johnson *. This last beautifully sculptured Helix 

 belongs to the group which includes Helix tiarella, Webbe, 

 once, living in most extraordinary profusion in Madeira, as 

 evidenced in the fossil deposit at Canical, but now rare. It 

 is a question whether this and other allies should not be 

 united under the name H. tiarella, for although they do not 

 intermingle either in locality or form, the remarkable sculp- 

 ture is nearly alike in all. By a parity of reasoning to that 

 which led Wollaston to unite a number of local forms as 

 varieties under the name H. polymorpha, the species to which 

 I refer might be aggregated under H. tiarella. I rediscovered 

 the shell now named H. Watsoni in an extremely limited 

 area of a few square yards only. Not being able to name 

 the form, I showed it to my friend Mr. J. Y. Johnson, the 

 eminent naturalist on the island. He recognized it, and 

 brought out from his stores two or three specimens which had 

 been found by Signer Moniz on the Ilheo dos Embarca- 

 douros many years before. Mr. Johnson told me that 

 Signor Moniz had no recollection of the exact spot on which 

 he had taken it, and although it had been subsequently 

 sought for by Sign or Moniz and other friends of Mr. Johnson, 

 it had not been again found. It was my good fortune during 

 the two hours I spent on the islet not only to procure in 

 plenty the species I had gone there to seek, and which are 



* "Description of Helix Watsoni, n. sp., from Madeira," by J. Y. 

 Johnson, Journal of Conchology, vol. viii. 1897, p. 429. 



