Prof. H. Karsten on Rhynchoprion penetrans. 295 



Humboldt, Voyage du Nouveau Continent, 1820-1822, torn. vii. cap. 19. 

 p. 250, and cap. 20. p. 129. 



Dumeril, Considerations generates, 1823, pi. 54. figs. 4, 5. 



Latreille, Regne Animal, 1829, iv. p. 351. 



Kirby and Spence, Introduction, 1828, vol. i. p. 102. 

 *Pohl, Reise in Brasilien, 1832, i. p. 106. 



Aug. St.-Hilaire, Voyage dans Rio Janeiro, 1830, i. p. 35, and Voyage 

 du Bresil, 1833, i. p. 228. 

 *Rengger, Reise nach Paraguay, 1835, p. 274. 



Waterton, Loudon's Magazine of Natural History, 1 836. 

 *Dugh, Annales des Sciences Naturellcs, 2 ser. tome vi. 1836, p. 129. 

 *Guerin-Meneville, Iconographie du Regne Animal, Insectes, p. 12 (Der- 



matophilus). 

 *W. Sells, Transactions of the Entomological Society, vol. ii. p. 195. 

 *J. O. Westwood, Ibid. p. 199 (Sarcopsylla penetrans). 

 *Tschudi, Peru-Reiseskizzen, 1846, i. p. 310. 



R. Schomburgk, History of Barbadoes, 1847, p. 652. 

 *Burmeister, Reise nach Brasilien, 1853, p. 284. 



All these descriptions originate in tropical and subtropical 

 America, in the region which has always been regarded as the 

 sole country of Rhynchoprion penetrans; the insect does not 

 occur in other parts of the world. 



Adanson, indeed, in his ' Voyage to the Senegal' (1757), men- 

 tions a kindof verysmallFlea, which resides in extraordinary quan- 

 tities in the sand of the huts, for which reason it has received 

 the name of the Sand-flea; but, from his further statements, it 

 appears that he does not refer to the Pulex penetrans, Linn.; for 

 he says, " Fortunately its puncture is not very painful, and it 

 consequently produces so intolerable an itching only because it 

 attacks the body in such great numbers. The most remarkable 

 circumstance," adds Adanson, "is that the insect usually does 

 not creep or leap to a greater height than three inches." The 

 latter peculiarity, like the name, reminds us of R. penetrans ; 

 but, if it had been this species, Adanson would certainly have 

 given us a fuller account of it. 



The most southern habitat of Rhynchoprion is that given by 

 Dobrizhoffer and Azara, namely, Paraguay, under the 29th de- 

 gree of south latitude. According to Auteroche, it is very 

 abundant in Vera Cruz, in 20° N. lat. ; and from the same au- 

 thority, as also from John Smith (cited by Sloane), the insect 

 appears to occur up to the latitude of Virginia, about 30° N. 



Everywhere the insect, which affects warm and dry places, is 

 met with in the vicinity of human habitations, either occupied 

 or deserted. All the accounts of the occurrence of this animal 

 in fields, woods, and plantations are due to confusion with spe- 

 cies of Ixodes, except when these statements refer to the leaf- 

 huts made by field-labourers or travellers to give tbem shelter 

 /or a night or for a short time. Such huts or leafy roofs, when 

 deserted by human inhabitants, usually become the dwelling- 



