THE CRUSTACEA OF NEW JERSEY. 67 



Sida crystallina (Miiller). 

 Plate 12. 



Daphne crystallina Miiller, Zool. Dan. Prodrom., 1776, p. 200. Denmark'. 

 Sida crystallina Herrick, Geol. N. Hist. Surv. Minn., Zool. Ser., II, 1895, p. 

 147, PI. 35, figs. 13-15, PI. 37, figs. 1-2 "ubiquitous." 



Description. — Body elongate, somewhat ovate, transparent, 

 and truncate posteriorly. Head large. Eye large, round. Body 

 as seen in shell narrow and nearly straight. Abdomen at pos- 

 terior angle with knob, from which two long set?e protrude. 

 Edges of carapace without any setae. End of abdomen with 

 two long curved pointed claws, shorter than seta? mentioned. 

 Between latter and terminal claws a series of about twenty short 

 spines along lower edge of abdomen. Also another superiorly. 

 Superior antennae rather large, long, armed at end with four short 

 stout spines. Inferior antennae large, with stout basal joint, 

 more than third length of whole limb, and with three short 

 spines on anterior extremity. External branch of three articula- 

 tions, first very short and with small spine at outer angle, other 

 two subequal. Inner branch of two joints, first much larger. 

 Feet in six pairs, each of three articulations, and with several 

 strong setae. Transparent. Length 3 mm. 



Remarks. — Known to me only from several examples I secured 

 in July of 19 12 in a tributary of Crosswicks Creek near Trenton, 

 in Mercer County. The species was not common and but few 

 were found among the multitudes of Cyclops, Scapholeberis and 

 other minute crustaceans gathered. I was, however, enabled to 

 make the above notes and thus include the species in our list. 



According to Baird "the motion of Sida through the water is 

 a sort of rapid running movement. They are generally inactive, 

 and adhere in a peculiar manner by the back of their head to 

 the side of the vessel in which they are contained, remaining 

 there for hours. Thev' adhere most probably in the same v^^ay 

 to the weeds in the water where they are found, as it is by 

 skimming the stems of the weeds that they are detached and 



