392 CRUSTACEA ENTOMOSTRACA. 



Eucyiherura G. W. Miill., Sclerochilus Sars ; Cytherois G. W. Miill. , the 

 members of this and the two following genera have suctorial mouth parts 

 and live on the juices of water-plants. Paradoxostoma Fisch., Para- 

 cytherois G. W. Miill. ; Microcythere G. W. Miill., Bythocythere Sars, 

 Pseudocy there Sars, Paracythere G. W. Miill., Jonesia Brady, Normania 

 Brady, Limnicythere Brady. 



Fam. 7. Cytherellidae. This family, consisting of the single marine 

 genus Cytherella Bosq. apparently represents a primitive form of the 

 Podocopa. The regularly arranged thickened bands in the hinder part 

 of the body give rise to a suggestion of segmentation, but this appears 

 not to correspond with the segmentation indicated by the limbs. The 

 outer ramus of the 2nd antenna is larger than in other Podocopa, and 

 the brush-shaped organs of the male, which probably represent an eighth 

 pair of appendages, are situated behind the last pair of limbs. The 

 divisions of the caudal fork are lamellar and fringed with stout bristles. 



Fam. 8. Darwtnulidae. This consists of a single fresh-water species 

 Darii'inula stevensoni Brady and Robertson. The anatomy is not com- 

 pletely known, but the species appears to lie allied to the Cypridae. 



Order 4. COPEPODA.* 



Entomostraca with elongated, usually ivell segmented body, without 

 shell-forming reduplications of the skin, and ivith biramous swim- 

 ming feet. f The abdomen is without appendages, and the eggs are 

 usually carried by the female in single or paired sacks attached to 

 the anterior abdominal segment. 



The order consists of a very large number of species of small 

 active free-swimming Crustacea, and of a variety of forms which 

 have to a large extent lost their power of free locomotion and 

 live as external parasites on other animals. While many of the 

 latter present no great departures from the type of structure 

 met with in the free-living groups, in others the Copepod and 



* 0. Fr. Miiller, Entomostraca sen Insecta testacea, quae in aquis Daniae 

 et Norvegiae reperit, descripsit, Lipsiae, 1785. Jurine, Histoire des Monocles, 

 Geneve, 1820. W. Lilljeborg, De crustaceis ex ordinibus tribus : Clado- 

 cera, Ostracoda et Copepoda, in Scania occurrentibus, Lund, 1853. C. 

 Claus, Die freilebenden Copepoden, Leipzig, 1863. C. Grobben, Die 

 Entwickelungsgeschichte von Cetochilus septentrionalis, Arb. des Zool. 

 Instituts, Wien., Tom 3, 1881. C. Claus, Ueber die Maxillarfiisse der 

 Copepoden etc., ibid. 11, Heft. 1 (1895). M. H. Hartog, The Morphology of 

 Cyclops, etc., Trans. Linn. Soc. Vol. V. pt. I. p. 1 (1888). W. Giesbrecht, 

 Die pelagischen Copepoden etc., Fauna and Flora des Golfes von Neapel, 

 1892. Idem., Asterocheridae, ibid., Bd. 25, 1899. Giard, Sur le parasitisme 

 des Monstrillidae, Comptes Rendus, T. 123 (1896), p. 836. Malaquin, 

 Le parasitisme evolutif des Monstrillidae, Arch. Zool. exp. (3), T. 9, p. 

 81. Hansen, Choniostomatidae , Copenhagen, 1897. 



t The name Copepoda has reference to the oar-like character of the 

 divisions of the swimming feet in the free-living forms. 



