187$.] HEMIPTERA OF ST. HELENA. 457 



identical with another, Cape-of- Good-Hope species — the significance 

 of which latter facts will be alluded to in connexion with the flora. 

 Again, the genus Euxestus was known from Madeira only, till Mr. 

 Wollastpn discovered another species in St. Helena. 



But as the most remarkable fact in the coleopterous fauna of St. 

 Helena i3 the enormous preponderance of Cossonidce — more than a 

 quarter of the endemic species belonging to that family — which 

 seem to find there their metropolis, we ought, if the line of migra- 

 tion is by Madeira &c, to find in the latter a significant development 

 of this family. And so we do. " In the Madeiran and Canarian 

 groups," writes Mr. Wollaston 1 , "there is scarcely any fact [the 

 insular-loving nature of the Cossonidce] more distinctly observable — 

 where every detached rock is tenanted by some one representative, 

 or more, of this particular department. Nor are trees and shrubs 

 (which seldom flourish in localities thus weather-beaten and exposed) 

 by any means essential for their support, the pithy stems of the 

 ordinary plants being amply sufficient to sustain them ; and I have 

 frequently found the stalks of dead thistles and Umbelliferse to be 

 perforated through and through by their ravages." Mr. "Wollaston 

 found 19 species in Madeira and 14 in the Canaries. The Anthri- 

 biidce (which include the next largest number of endemic species in 

 St. Helena) indicate a like derivation ; but enough has, I think, been 

 brought forward to show both the Palsearctic origin and probable 

 route of migration of the Coleoptera of St. Helena. 



The Hemiptera are not fitted (from the reasons already given) to 

 teach us so much as the Coleoptera ; but 12 at least, if not all, of the 

 13 non-peculiar genera are Palsearctic, and many of them Madeiran. 

 The peculiar genera have also nearly all strong affinities with Palse- 

 arctic genera. Just as the whole facies of the Madeiran Hemiptera 

 is European, so that of the St.-Helenian is Madeiran and European. 



The characteristics of the Arachnida and of the terrestrial Mol- 

 lusca have already been pointed out. 



But let us now see if there be any thing in the manner of life of 

 the aboriginal animals of St. Helena which would make their passage 

 across the sea not only a possible but a probable occurrence. If we 

 can find that a majority of them are connected with plants, it is not 

 difficult to imagine how they might have been drifted by sea- 

 currents to the island ; but if, in addition, it turned out that many 

 inhabited the interior parts of plants, their carriage across the sea 

 would pass from the region of possibility into that of probability. 

 Mr. Wollaston has carefully recorded the modus vivendi of the St.- 

 Helenian Coleoptera ; so we will try and prove our case from his 

 evidence. 



At least half of the 12 endemic species of the genus Bembidium 

 have the very abnormal habit, for that genus, of living icithin the 

 dead and rotting stems of the tree ferns. (I may note here that in 

 the Madeiran group 10, in the Canaries 14 (7 peculiar), and in the 

 Cape-Verds 5 species of the genus have been found.) The 

 following St.-Helenian genera are also, amongst others, especially 

 1 Trans. Entom. Soc. London, 1873, iv. p. 433. 



Proc. Zool. Soc— 1878, No. XXX. 30 



