294 Dr. J. Vosseler on the 



4. Cyclops agilis, Koch, 



and that in all ages. A species very nearly allied to this, 

 which, as an inhabitant of all tlie " Maare " examined, is 

 characteristic of these waters, and which has not yet been 

 described, I name 



5. Cyclops maarensiSj sp. n. 



The thorax (embracing the first four segments) is elongate 

 ovate. Its last (fourth) segment bears five hairs at the 

 postero-lateral margin. The abdomen has a slender appear- 

 ance owing to the delicate furca. The first antennae are 

 twelve-jointed and do not reach to the extremity of the long 

 cephalothorax (first body-segment). In the first third of the 

 fourth joint of these antennre a strong seta is remarkable for 

 its length. The last three joints gradually increase, but all 

 three are of small size. The second antenna? are short and 

 stumpy. The labrum is deeply incised in the middle and 

 bears eight larger and four smaller teeth (the latter two on 

 each outer side) . The buccal organs are remarkable for their 

 feeble development. The swimming- feet are long and bear 

 at the tips of their branches stiff spines, resembling lance- 

 heads serrated on both sides. The fourth pair of feet, when 

 laid close to the body, reaches beyond the genital aperture. 

 The last joint of the outer ramus bears three spines in the 

 first pair of swimming-feet, four in the second, four in the 

 third, and three in the fourth. The rudimentary foot consists of 

 a single joint, with a strong spine on the inside, and furnished 

 with a seta at the apex and on the outside. The last segment 

 of the abdomen, which bears the furca, is finely hairy at the 

 hinder margin ; the preceding segments are toothed. This 

 species is very easily recognizable by the furca, whicli is 

 remarkably slender and longer tlian the three preceding abdo- 

 minal segments. The external lateral seta is ])laced about 

 the last (posterior) fourth of the length of the furca. Above 

 it a half-circlet of small hairs winds spirally forward and 

 outward. Of the terminal setee I found only the two middle 

 ones hairy. In the male these seta? are characterized by 

 remarkable inflations in the first half. The adult female 

 measures 1*8 millim. including the caudal setee, the male 1'2 

 millim. The ovisacs are borne in the same way as in C. 

 agilis. 



This new species is distinguished from C. agilis, Koch, 

 by absolutely and relatively shorter antennse, fully developed 

 buccal organs, and an extraordinarily elongated furca. While 

 the latter in C. agilis is serrated at the outer margin, in C. 



