CYCLOPS. 



[ 225 ] 



CYCLOTELLA. 



consolidated with the first and largest joint 

 of the thorax ; last joint of abdomen con- 

 sisting of two separate lobes. 



Superior antennae (figs. 8, 9 a) composed 

 of many joints (twenty-six, Baird), from 

 each of which one or more setae arise ; in 

 the male, each superior antenna exhibits a 

 swelling at about its middle (fig. 8 &), fol- 

 lowed by a sudden contraction, the first 

 articulation of which forms a hinge-joint ; 

 inferior antennae (fig. 9 6) four-jointed, each 

 joint with setae, the terminal with six of 

 unequal length. The mandibles (fig. 11) 

 consist of an ovate body (a), narrowed and 

 twisted above, and terminating in a number 

 of brownish teeth, with a marginal serrated 

 seta (b) ; each mandible has also a palpus, 

 consisting of one segment and two long 

 filaments. 



Behind the mandibles, the first pair of 

 foot-jaws (fig. 12) are situated ; each con- 

 sists of a body, convex externally, concave 

 internally, furnished at the end with two or 

 three strong teeth, and with a single-jointed 

 palp-like organ terminated by setae. 



The second pair of foot-jaws (fig. 13 a 6) 

 are divided to the base into two portions ; 

 an internal (6) smaller, and consisting of 

 four joints, each with one or more setigerous 

 spines, the last with three ; and an external 

 (a) composed of three joints, to the base of 

 the first of which the internal portion is 

 attached ; this first joint is the longest, and 

 furnished on its inner side with two tuber- 

 cles, each with one or two setigerous spines, 

 a longer jointed spine arising from near its 

 distal extremity ; the second joint is fur- 

 nished with two strong claws of nearly equal 

 size ; and to its upper edge is attached the 

 third joint, smaller than the second, also 

 furnisned with tw r o claws; some of the 

 spines are themselves setigerous. 



There are five pairs of legs or feet, four of 

 which are branchial, uniform, and arise from 

 the thoracic segments. Each of these legs 

 (fig. 14) is composed of two branches arising 

 from a common base ; each branch is three- 

 jointed, and each joint is furnished with 

 elegantly plumose setae, the last having six 

 or seven. The fifth pair of legs (fig. 15) are 

 rudimentary, and arise from the first and 

 smallest segment of the abdomen ; they are 

 two-jointed in the female, and three-jointed 

 in the male. 



The external ovary (fig. 9) communi- 

 cates directly with the internal by means 

 of a small canal on each side between the 

 first and second segments of the abdomen. 



The tail consists of two lobes, each termi- 

 nated by four variously setigerous filaments, 

 the two intermediate being the longest, and 

 jointed near their origin ; sometimes there 

 are two joints to each, and the outer ones 

 are also jointed. 



Scarcely a pool of water can be found in 

 which this animal may not be seen darting 

 about in various directions. It varies greatly 

 in structure and appearance, according to 

 age, locality, sex, &c. ; and these varieties 

 have been admitted as so many species by 

 some authors. 



PI. 20. fig. 16 represents a recently hatched 

 Cyclops (Nauplius-form). 



The individuals are frequently covered 

 with Vorticellesand. other parasitic Infusoria. 



BIBL. Baird, Ent. 198 ; Koch, Deutschl. 

 Crustac.; Claus, Wieg. Arch. 1857; Tr.M. 

 Soc. 1880, 251; Brady, Copep. (Ray Soc.\ 



CYCLO'SIS. See ROTATION. 



CYCLOSTO'MATA. A suborder of 

 marine Infundibulate Polyzoa. 



Families : Tubuliporidse, Crisiidae, Hor- 

 neridae, and Lichenoporidae. 



CYCLOTEL'LA, Kiitz. A genus of 

 Diatomacese. 



Char. Frustules free or adherent, disk- 

 shaped, mostly solitary; valves circular, 

 flat, convex, depressed or undulated, stria- 

 ted ; striae radiating. 



The frustules of some of the species are 

 immersed in an amorphous gelatinous sub- 

 stance. 



When the valves of (all?) the species 

 of Cyclotella are examined under an object- 

 glass of large aperture, with the central 

 stop (!NTB. p. xix), the surface is found to 

 be marked with dots in radiating rows, as 

 in some species of Coscinodiscus -, hence 

 these two genera should probably be united. 

 Some appear to represent the frustules of 

 Melosira seen in end view. 



C. opei'culata, K. (Pyxidicula operculata, 

 E., Discopka Kutzingii, E.) (PL 16. fig. 21 ; 

 , side view ; &, front view). Angles of 

 frustules in front view rounded ; strife ob- 

 scure, very short, giving the margin a punc- 

 tate appearance; freshwater; diameter 

 attaining 1-1000". 



)8. rectangula, K. (C. Kiitzingiana, S.) 

 (PI. 16. fig. 22). Angles of front view not 

 rounded ; striae more distinct. 



C. Meneghiniana. Valves plane, distinctly 

 striated at the margin ; fr. wat. ; length 

 1-1440". 



/3. major. Twice as broad. 



C. antiqua.) S. (Discopka atmosphenca, 



Q 



