660 CLASS X. 



others, as Orchestia littorea, under the name of Cancer pulex, Syst. nat. e 

 12, i. p. 1055!. 



Gammarus pulex FABR., GERV. is very common in ponds. The fema 

 carries her eggs under the body at the base of the feet, until the youn 

 emerge. RCESEL saw the animals nibbling at roots, fruits, and other par 

 of plants which he gave them. Usually, however, they live on anim; 

 food, and according to DE GEER, do not spare even the bodies of the 

 companions. They attain a length of about 2". The hinder end of ti 

 body is always bent downwards. Compare also on this species J. ( 

 ZENKER De Gammari pulicis FABR. Hist, naturali et sanguinis circuit 

 commentatio. Accedit Tab. ten. Jenae, 1832, 4to, and, on the difference < 

 the two species, GERVAIS Ann. des Sc. nat. 2e Se'rie, IV. 1835, Zoologi 

 pp. 127, 128. 



OEDER IX. Stomatopoda. 



Two compound eyes, placed on a biarticulate moveable petiole 

 Antennas four, placed nearly in the same horizontal row; interna 

 long, terminated by two or three multiarticulate setae, externa 

 mostly furnished at the base with an oval ciliated lamina. Feet o 

 trunk mostly in seven or six pairs, more rarely eight. Moutl 

 inferior, often situated between the bases of anterior feet. Branchia 

 mostly adhering to the caudal feet, more rarely to the thoracic, neve: 

 covered. Tail mostly terminated posteriorly by a foliaceous pinna 

 Shell thin, in many almost membranous. 



Family XXIV. UnipeUata. Body elongate, narrow. Cephalo- 

 thoracic shield elongate, often produced over the back of the ante- 

 rior segments of trunk. Anterior segment of cephalothoracic shield 

 bearing the middle antennae and eyes, distinct. One pair of max- 

 illiform feet slender, elongate. Seven pairs of feet in trunk 01 

 thorax; first pair large, with last joint mostly falcate, dentate in- 

 ternally; second, third and fourth pairs shorter, approximate to 

 mouth, terminated by an oval hand and moveable hook; three last 

 pairs slender, remote, mostly furnished with a styliform appendage. 

 Of caudal feet six pairs; the first five mostly bearing branchiae of 



1 From a passage in the Fauna Suecica p. 246 "habitat ad littora marts vulga- 

 tissimus" it would seem, that LINNAEUS probably by Cancer pulex had a species in view 

 different from Gammarus pulex or fluviatilis, perhaps Gammarus locusta FABR. ; that 

 he also confounded Orchestia with it appears, however, from his citation of BASTBB. 

 Hence it is impossible to quote with justice Cancer pulex L. as a synonym of a 

 determinate species. 



