438 CRUSTACEA. 



they form a c^lrront in the water. In the mri]es,l)Oth or one of them are constricted anil knottcJ. The upper an- 

 tennas were, previous to the researches of Jariue, cun^iduiTd as organs of g'eneratioii, fi'oni tJic iiiaiiin.'r in \\]ii';li 

 they are used during coupling-. The females are iiiuvidcd, on each side of the tail, with an o\ul sac, or external 

 ovary, filled with eggs, and attached by a very slender [leduncle. A single act of imprc;?iiatioii is snihcient for 

 several successive generations. The female is able to produce as many as ten broods in the course of three 

 months. At their birth, the young have only four feet ; and the body is rounded, and destitute of a tail. These 

 individuals were considered by M idler as forming a distinct genus, named /f7»////(t(He. Some time aftenvards 

 (fifteen days in February and March), they acquire another pair of legs, in which state they constitute Miiller's 

 genus Ntntplius. After the first nioidting, they have the same form and organs as the perfect insect, but the 

 latter are of smaller size. After two more niouitings, they are able to propagate their species. The majority of 

 these Crustacea swim back downwards, darting about with great agility, and moving botli Ijackwards and for- 

 wards with equal ease. In the absence of animal matter, they attack vegetable substances. 



Ci/cfops stajilnilhuis — in its shorter antenna;, which vary in the number of their joints, and in the gradual nar- 

 rowing of the body, as well as in the curved corneous point with which the under-side of the base of the tail is 

 aj'med — forms a separate division in the genus. 



Ciidops ca^/o/-, and some other species, having the antenna; and mandibular palpi divided into two branches, 

 form another division. 

 The subgenus Calanus of Leach is described as having no inferior antenna? ; — but is this statement original? 

 llie Xy\)e of the genus is the Cyclops quailricomis (Moiiociili/s quadrlcornis, Linn. ; and C. vidyaris. Leach), 

 which has all the antennae single, and not divided. The body is ovoid, and the tail six-jointed. 

 The colour varies considerably, some individuals being reddish; others whitish or greenish. 

 The length is cne-lifth of an inch. It is very abunflant. 



[W. Baird, Esq., has published a very complete memoir upon this genus in the fourth num- 

 ber of the Magazine of Zoologij and Botany, giving the bibliographical history, anatomy, and 

 economy of the genus, with a monograph of the British species, in great detail. He has given, 

 after Jurine, a calculation, whereby it appears, that at the end of one year, a female which 

 gives birth to forty young at a time, may become the progenitor of 4,442,189,120 young! He 

 has corrected Latreille's obsen-ations relative to the genera Amymorne and NfnipUu.s, the 

 Fiff. 17.— f'ycioiis species of which the former genus was composed consisting of the young of C. miiniliis in ilif- 

 vu yiirrv, Liia(rii! e . f,.,.Q^it t^tates, which nevcr assume the form of Naiiplius, whereas the Naiiplins is tlie young of 

 C. </i'in/r/i-<>nijs. II'-' considers them to be decidedly carnivorous.] 



[_Mr. Trniiilrtdh has described some beautiful species belonging to this genus, in the tii-st volume of the Truns- 

 ariioiiN of the Entomological liociefy, from the Island of iMauritius. One species (C. \_<Ja(fniu-s] arietis) is remarkable 

 for the great length of its superior antenna;, which are armed near the tip with two very long recurved setai. The 

 Cyclops (Anomalocera) Padcrsonii, described by the same gentleman in the second volume of the same work, is 

 closely allied to Cyclops castor. The males of both species are remarkable for having one of the antennu: greatly 

 swollen beyond the middle, the other being simple.] 



[Ci'locliilii.s iif \'auzeme is a singular genus, dillering from Ci/cloj/s in having a pair of eyes. They have two very 

 long, and t^vo very short antenna: ; five pairs of short foot-jaws ; five pairs of swimming, bitid, and ciliated legs ; 

 and a small, narrow, 5-jointed abdomen. Type, Cetochilus australis (Yauzeme in Ann. fyci. A^af., 1834), a species 

 found, in inconceivable profusion, beyond 42 of south latitude, in the Pacific and Atlantic Oceans, giving the sur- 

 face of the sea a red tint, and sen'ing as the food of the whales.— See Brit. Cyclop. Xaf. Wsf., vol. i. ii. 790.] 



Tlie second general division of the Branch ioj>o(/a Lopln/ropa — that in wliicU the shell is formed 

 of two valves united by a fleshy hinge, and inclosing the body "nhen in inaction — have only six [or 

 eight] legs, none of wbicli are terminated by a branching swimmeret, accompanied by a branchial 

 ])lat(:. Tlie antennae arc bini])lo ; they have only one eye; the mandibles and anterior maxillse are pro- 

 vided with a branchial plate; and the eggs are carried beneath the back. These coni[iose our Os^tra- 

 CODA, or the order Osirapoda of Strauss, and consist of two subgenera, of \\liich tlic first, (Syihere, 

 appears to require a more minute examination than has been given tu it by Midler, who is our only 

 authority, especially stnce the elaborate researches of Sti'aiiss upon the second siihgenus, Ci/j/ris. 



Cylhcrc, MCill., Ciitlirrina, Lam., lias, according to Miiller, eight simple legs terminating in a point, and two 

 antenna', aKo siniple, setaceous, 5 or 6-jointed, with hairs scattered upon them. The species are funud in 

 salt and brackish water, near the shores of the sea, amongst sea-weed and conferva'.* [Mi', 

 fully examined the structure of these animals, states that they have decidedly eight feet ai 

 that they are only found in sea water, — Mnfj. of Zonl. and Bof., ii. 139.] 



Cyj>ris, I\liill., has only sixf legs, and Mirii U\o antenna; are terminati'd by a i)enci[ nf [In 

 is in the form of an oval body, conipre.-.sod at the sides, arched and swullcn at (lie bad-;, or | 

 is plarcd ; nc;.|-|y sh-;tiiiht. or a little incised and kidney-sliniicd, ini the oflirr side. In trend . 

 tlie nuil-lMjr !,{ the Ijody, tin; single e\e forms a large blark and niund sput. Tlic anteiiu 



miwullou 10 tliL 



