AMERICAN PARASITIC ARO VLID^WILSON. 731 



shaped spines. The swhnining- legs are the same as in Argulus, but 

 the third pair have a smaller Hagelhim in addition to the inWy devel- 

 oped ones on the hrst two pairs. The endopodite of the first pair is 

 without joints. Both basal joints of the posterior pair are furnished 

 with large flat flaps, which underlie the base of the abdomen. The 

 testes of the male are divided longitudinally into narrow lobes, two in 

 some species {longlcmida, etc.), and three in others {ranarmn, etc.), 

 in each testis. The accessory copulatory organs in longicauda show 

 the regular peg and semen receptacle, with the addition of large 

 finger-like protuberances on the anterior border of the third legs. 



In the female of domdis the papillfe on the ventral surface connected 

 with the semen receptacles are long and finger-like, and seem to be 

 destitute of spines. 



The position of the anal papilla is not given for any species except 

 rcmm-wn; doradis has a pair of very rudimentary papillaj at the 

 opening of the oviduct, but in none of the other species are they 

 mentioned. 



After this paper had been placed in the printer's hands the U. S. 



National Museum secured from the Paris Museum specimens of both 



sexes of the species Dolops reperta, doradis^ ranarum, and hldentata. 



These were kindly placed in the author's hands for examination, and 



through them the facts relative to those species have been verified. 



At the same time the author was fortunate enough to secure Bouvier's 

 Memoir on the genus Dolops (1899*^), from which the facts relative to 

 the other species of the genus have been obtained. 



Bouvier deals with external anatomy only, and makes no mention of 

 the internal structure. 



So far as could be determined f rorii tne preserved specimens just 

 mentioned, the internal anatomy corresponds very closely with that in 

 Argulus. 



Nothing could be seen of the nervous system except the brain and 

 here and there a peripheral nerve; but these were almost identical in 

 shape and position with the corresponding portions of the nervous sys- 

 tem in Argulus. There is a heart placed similarly to that in Argulus, 

 with a short anterior aorta (Stuhlman), and the l)lood takes much the 

 same course in circulation, save that in the al)domen the outgoing cur- 

 rent passes backward along the margin and returns through the cen- 

 ter, just the reverse of the course in Argulus. 



The digestive system is practically the same as the one already 

 described. Whether the reproductive organs are similar to those in 

 Argulus could not be determined with certainty. The semen recep- 

 tacles of the female are located in the same position in the abdomen, 

 and there are two minute papillte, one on either side, just posterior to 

 the oviduct opening, where the hollow papilla were found in Argu- 

 lus, and in all probaliility these in Dolops are similar in function, if 

 not in structure. 



