INTEEXAL ANATOMY OF BDELLA. 479 



should not like to speak with absolute certainty ; but the palpus of his species is similar 

 to that of B. Bastei'i (as I found it), and is not similar to the paljms of any other Bdella 

 which I know of. 



Bdella tnarinu, Packard *, is probably also the same species. 

 . Enpalus smiguineus, Trouessartf, is also a synonym (according to the author himself). 



Bdella villosa, Kramer and Neuman J, is either the same species or a very closely allied 

 one ; but in the figure the fifth joint of the palpus is drawn a trifle shorter than the 

 second, whereas in B. Basteri the second is a trifle shorter than the fifth; and the spines 

 at the end of the fifth joint are drawn rather longer than those at the side, whereas in 

 B. Basteri they are about equal in length : these, however, arc small points, and the 

 probability that the creatures are identical is increased by the fact that Trouessart 

 received some of his specimens of B. Basteri {sanguinea) from Iceland, and these had 

 the fifth joint of the palj)us rather shorter than, in the French specimens, so that it seems 

 probable that B. villosa is at most a local variety. 



I think there is very little doubt that Bdella arctica, Thorell, 1871§, is the same 

 species, although here again the fifth joint of the palpus is said to be slightly shorter 

 than the second. 



Bdella lapidaria, Kramer, 1881 (i 2. p. 28, Taf. 4. figs. 9, 9 «, 9 b,), and Bdella vulgaris, 

 var. littoralis, Mouiez, 1890 (15), arc both sea-shore species, but they ai*e not identical 

 with B. Basteri ; Trouessart suggests that they are probably both the same species. 



I am also greatly indebted to Mr. M. J. Michael, of the Davos Platz, Switzerland, who 

 has cut the sections which I have used for the present study, and has otherwise 

 assisted me. 



The Bdellinse are usually considered to be a subfamily of the Trombidiidse ; they are 

 a very aberrant subfamily, and are raised into a family by such acarologists as 

 Canestrini (3), Berlese ||, &c., who elevate the old family of the Trombidiidye iato 

 an order under the name of " Prostigmata '' (Kramer), Trouessart (20) considers the 

 Prostigmata to be a suborder, separates the Bdellinae from the Trombidiidte, but unites 

 them with the Eupodinaj to form a family "Bdellidie"; his subfamily " Bdellinye," 

 however, contains the same two genera for which I vise the term in this paper, but it 

 also contains one other, Qrijptognathns (Kramer), which appears to me to be too different 

 to be included. The two genera which I include in the Bdellinae are Bdella (LatreiUe, 

 1797) and Ammonia (Koch, 1842), distinguished according to Canestrini (2. p. 181), 

 following Kramer's subdivision of the genus Bdella, by the long rostrum and long 

 mandibles with very small chelae of Bdella, compared with the shorter rostrum and 

 mandibles and comparatively substantial chelse of Ammonia; but distinguished according 

 to Bevlese (1) by the second and third joints of the palpus being more or less fused, and 

 by the presence of a fifth median eye and the absence of hairs between the claws in 



* ' The American Naturalist,' 1S84, pp. 827, 828, iig. 2. 



t Comptes lleudus de FAcad. d. Sci. 1S8S, t. cvii. jjp. 753, 755. 



+ "Acariden wahrend dcr Vega-Expedition eiugesammelt," Yega-Expeditioneus Yetonskapliga Arbeteii, Bd. iii. 

 p. 525, Tail. 41. 



§ " Om Araelinider Mu Spetsbergen och Becren-Eiland," CEfversigt K. Yet.-Akad. Forhaudlg. 187 1, Stockholm, 

 p. 698. 



li "Acarorum systematis Specimen,'" Boll. Soc. Entom. Ital. 1885, pp. 121-125. 



65* 



