COPEPODA 



The main points to be noted in the specific determination of the Rcnus ut: 

 length and number of segments in the antenna of the female; 

 armature of the antennal segments, espcciallv oi the lermiiuU'scjfmcnlA; 

 form of the abdomen, especially the form and armature of the (ureal rami' 

 form and armature of the rudimentary- fifth feet; 



structure of the second antennae, of the maxillii)e<les. and of the swimminic feet 

 These last structures are of less importance. 



77 (98) Antennae composed of twelve or more segments. 



78 (92, 93) Antennae composed of seventeen segments 71; 



79 (80) Fifth feet composed of one segment armed with one sf)inc anci 



two long setae Cyclops atcr Hcrrick i88i. 



It is a large dark-colored species, rather rare, probably diMrihutc«l very 

 widely, and growing in shallow water. In spite of its 'wide dinnbutian. 

 however, it is a rare form. 



Length of female, 1.77 to 2.88 mm. 

 Fig. 1213. Fifth foot of Cyclops atrr. X J'/). iOri<inAl . 



80(79) Fifth feet composed of two segments. . ^I 



81 (84, 89) Second segment of fifth feet armed with seta and short spine. 82 



82 (83) Spine of second segment of fifth feet small and near i-nd of .v-g 



ment; last three segments of female antenna without hya- 

 line membrane Cyclops viridis J urine i8io. 



Fig. 1 2 14. Abdomen of fe- 

 male Cyclops viridis, var. 

 americanus. X 77> (Origi- 

 nal.) 



Fig. 1 2 15. Abdomen of 

 female Cyclops viridis, 

 var. brevispinosus. X 

 66. (Original.) 



Cyclop 



(or 



Fi/lh (oo« ol 

 tiridii. X ilS. 



ruciiuil. 



(1 laki-s. 

 mil) 



A widely distributed species, being found both in jxxils anc 

 form and general appearance, so that it has receive<l a number of ditlerrnl 

 which are now reduced to varieties, since it has been ftuind that there arr intr 

 showing all the stages between the extremes. W he 

 colored, while its relatives living in the open waters ol 



It varies k'riMtl\ 

 litlerrnl 



III 



When living i'l l>«»*'b 



It IS apt t.. i< 'ri4y 

 )f our lakes are lolorli-ss and llm«»^i tran»- 

 par^ent? lEspVcially"nodcVabIe"is"th^^ the form of the fur..d r.n.i .v. ^h. wn in 



Figs. 1214 and 1215. The forms found in pools generally have com|Kirai: ■ A 



furcal rami; on the other hand, the forms in deep waters have Ions an.. «• 



Even in the Hmnetic forms there is wide variation. n typi. .U virulis tlu ;. . 

 the outer angle of the furcal ramus. This is replaced in the orm whuh Hrrr »• 



spinosus by a short broad spine. This variety is a common limnetic form u. « 



lakes; a form with the furca armed at its outer angle with a srta ''•j;' 'M»'; •" 

 from mridis in the structure of the swimming feet and ot the lilt 1 ic-rt. 

 common in shallow waters, and is the variety that is m.)st rt-quent y scrti ^^ 



United States. Wherever a collection is made one is likely to get some form oi i^.-w. *aa 

 generally it will be americanus. 



Length of female, 1.25 to 1.5 mm. 



