66 REPORT OF NEW JERSEY STATE MUSEUM. 



in female, but extending into very strong flagellumi in male. 

 Antennae long, biramose, with unequal branches. Mandibles 

 truncate at end. Maxillae armed with large spines. Form of 

 body usually elongate, and abdomen often extends beyond edge 

 of shell behind. Male openings usually in end of long append- 

 ages which depend fromi base of post-abdomen. 



Several genera in America, though only one known from New 

 Jersey. These animals are usually to be found in the clear and 

 colder waters of large lakes. They produce winter eggs, laid in 

 October, which differ from the summer eggs, which hatch in 

 the brood cavity, by a brorwn color and fatty spheres being pres- 

 ent. These eggs are produced in larg-e numbers, in distinction 

 tO' most other Cladocera, in which the winter eggs are very few. 

 The eggs fall to the bottom and there develop at the proper 

 time. Some formis occur abundantly in areas of plant growth. 

 As the size and reproductive energies are dependent on environ- 

 ment, but little success may be expected if their preservation in 

 aquaria is attempted. As some forms are nocturnal they should 

 be sought at the surface of the water on quiet evenings. 



Genus SI DA Milne-Edwards. 



Sida (Straus) Milne-Edwards, Hist. Nat. Crust., Ill, 1840, p. 385. Type 

 Daphne crystallina Miiller, monotypic. 



Body long, transparent. Head quadrate, rather small. For- 

 nices absent. Antennules of female small, truncate. Antennules 

 of male with long flagellmn. Second antennae with rami two 

 and three-jointed. Male with sexual openings just behind last 

 pair of feet. 



Species few. The reference to Straus, in Mem. Mus. Hist. 

 Nat. Paris, V, 1819, pp. 380-425, which I consulted, shows that 

 the generic name is not proposed there. The earliest I can find 

 is by Milne-Edwards in 1844, though it may have been used 

 previously. 



