300 Prof. H. Karsten on Rhynchoprion penetrans. 



skin, lymph flows continually from the wound, and a purulent 

 condition soon setting in converts the originally small wound 

 into a more or less extensive sore. 



The opinion expressed even by the first writers on this para- 

 sitic animal, and repeated by various later authors, that there 

 are two species of its genus, is founded by them partly on the 

 difference of coloration already referred to, and partly on the 

 length of the buccal organs. In all the animals examined by 

 me, however, the latter were at the utmost about one sixth 

 longer than in the common Flea, attaining scarcely half the 

 length of the body of the free animal ; whilst Linnseus and his 

 successors characterize this species by the piercing-apparatus 

 being equal in length to the whole body. From my own obser- 

 vations, I should have been the more inclined to regard this 

 statement as erroneous, because I do not find it noticed by any of 

 the predecessors of Linnseus with whose works I am acquainted 

 (I have been unable to find Rolander's statement with regard to 

 this insect, cited by Linnaeus), if Westwood did not expressly con- 

 firm the Linnsean diagnosis. Westwood examined the specimens 

 brought by Sells from Jamaica. Swartz also observed the 

 animal in that island, but he figures the mandibles as only of 

 the length observed by me. Is it possible that the limits of 

 distribution of two species of this genus of Fleas may coincide 

 in the Antilles, — namely, a long-beaked North American species 

 and a South American one with shorter buccal organs* ? West- 

 wood's figures of this animal, imperfect as they are, are favour- 

 able neither to this hypothesis nor to the accuracy of his inves- 

 tigations, as they also represent the mandibles of the usual 

 length. 



We are therefore at present with certainty acquainted only 

 with one species of Nigua ; the existence of a second species has 

 still to be demonstrated, although Westwood has already given 

 it a name by anticipation, calliug it Sarcopsylla Cams from the 

 supposition that it especially inhabits dogs, notwithstanding 

 that the Nigua taken from a dog, and fully described by Pohl 

 and Kollai', is regarded as belonging to the Linnsean species. 



For the earliest account of the different organs of which the 

 piercing-apparatus of R. penetrans is composed, as also of their 

 form, we are indebted to Duges, who detected the maxilla? with 

 their palpi, the median piercing-organ, the structure of the man- 

 dibles, and the presence of the labium. More recent observers 

 have not completed these statements; on the contrary, the 



* Besides the above-mentioned specimens of Rhynchoprion, brought by 

 Schmarda from Cuenca, and those which I observed in Venezuela and New 

 Granada, I have examined others brought by Dr. Carl Martin from San 

 Paulo, in Brazil, and entrusted to me for this purpose. 



