54 PROCEEDINGS OF THE ACADEMY OF [Jan., 



there should be a variety of C. fimhriatus, which he named C. fimhriatus 

 var. jJoppei Rehberg. 



All of Herrick's drawings of the stylets of what he describes as 

 C fimhriatus Fischer show that his specimens belonged to the var. 

 poppei, and not to the typical form. Forbes recognizes the varietj' 

 poppei, but gives no description or figures in connection with his 

 note of the occurrence of the species. Miss Byrnes, following 

 Herrick's mistake, has described this variety as the typical C. fim- 

 hriatus from Long Island. Her fig. 5, pi. XV, of the stylets with 

 their characteristic armature of a longitudinal row of spines proves 

 that the animal examined by her was not fimhriatus, but the variety 

 poppei of Rehberg. There has been not a little confusion of the 

 above-mentioned two forms. I cannot find a single description of 

 the typical C. fimhriatus Fischer by any American investigator. 

 The species seems to be represented in this country by the variety 

 only. This has been described at least twice under the name of the 

 type form. 



Cyclops fimhriatus var. poppei seems to be one of the rarer species 

 of. the genus. Several of the investigators have failed to find it. 

 Kofoid states in his Plankton of the Illinois River, "K. B. Forbes 

 ('97) records in May, September, 1896, C. varicans Sars as common, 

 and C. fimhriatus var. poppei Rehberg and C. bicolor Sars as rare." 

 Forbes states that this is "a rare species in Manitoba, Alabama, 

 and the north central States. " Brewer does not record it from the 

 waters about Lincoln, Nebraska. Marsh, in '95, names "fimhriatus'' 

 in his Key to Species of Cyclops, but gives no description. Miss 

 Byrnes has studied the species from Long Island waters, where she 

 states that "Cyclops fimhriatus has been taken in great numbers — 

 especially in the collections made in the early spring." This obser- 

 vation agrees very closely with my own regarding the variety poppei 

 in this vicinity. In a collection made in the spring (March) of 1907 

 it was the most abundant form. I have never recorded it from 

 September to January, In February, 1909, I found a few egg-bearing 

 females. I consider it one of the rarest of the members of the genus 

 found in this locality. 



Specific Description. — The somewhat slim cephalothorax (PI. IV, 

 fig. 5) tapers only slightly posteriorly. The first segment is half as 

 long as the entire thorax. The dorso-ventral diameter is short in 

 proportion to the length of the animal. In a specimen measuring 

 1.13 mm. it was but .14 mm. The width of the three posterior 

 thoracic segments diminishes but a little. The lateral angles of the 



