STATE GEOLOGIST. Ill 



Cypridae, Baird, Brit, Entomost., p. 130. 

 Characters. — Feet, two pairsj anterior slender and pediform, posterior weak; 



Abdomen elongate, bearing two clawed appendages. 

 The cyprinae, in common with all the members of this tribe are enclosed in a 

 brittle, mussel-like shell which hides from view, in general, all of body and 

 members, except the extremities of the two pairs of antennae and a pair of feet. 

 They vary in size from an animal of sufficient size to be easily watched with the 

 naked eye, and resembling a small Unto in shape and color, to creatures so 

 minute that it is with the greatest difficulty that the valves of the shell are 

 removed without destroying the parts within completely. This peculiarity of 

 these animals renders them among the most difficult in all this order to study. 

 The shell is usually opague. and sometime beautifully colored and fringed. 

 When, however, the soft parts within are separated from the crustaceous envelope 

 the beauty and peculiarity of the structure well repays the student. The shell 

 is composed of two valves, which are only united for a short part of the dorsal 

 margin, and which are held together by muscles which are under the control of 

 the animal. These valves are symetrical with each other in general and are 

 covered by a sort of varnish, which seems to repel the water s© that when the 

 creature takes air within the valves of the shell, and hence floats upon the 

 surface it is impossible to cover it with water to prevent the glitter from the 

 surface, while the air within prevents, by its refraction, a view of the interior 

 in such as are transparent. On removing the shell the body is seen to consist of 

 two parts, of which the anterior, or cephalothorax, is considerably the larger 

 and is furnished with organs as follows : first, the eye, situated on the upper 

 portion of the anterior aspect, which, according to Baird, has no crystallines. 

 By Dana, however, two lenses are described; second, the superior antennae, which 

 are in general seven -jointed, and setigerous. These organs are always kept in 

 vigorous motion when the animal swims. The setae are sometimes plumose; third, 

 the inferior antennae. These are more hke feet than antennae and are five -jointed, 

 and in one genus abundantly covered with (sometimes plumose) setae. In all 

 they are furnished with strong claws at the extremity; fourth, mandibles, which 

 are composed of two parts, the main portion consisting of a triangular plate 

 terminating below in a curved neck, bearing at the end a number of teeth. From 

 the base of the neck arises a second portion, which is three or four-jointed and 

 setigerous. From the end of the first ioint of this palpus springs a small plate 

 (branchial?) which has several fine filaments; fifth, first pah' of maxillae. These 

 organs consist of a basal portion and the proper maxiUae which are of two rami, 

 each ramus being furnished with setae. There is also an attached branchial plate 

 extending within the shell directed upwards and backwards; sixth, maxiUipeda. 

 These organs vary in Cypris, As figured by both Dana and Baird, they are of two 

 rami, or have a "maxillary process," but in the species of Candona here figured 

 they seemed to resemble the maxillipeds of the Cyclopoidea; seventh, first pair of 

 feet. These are five-jointed and terminate in a strong hooked-claw which is 

 directed forward, opposing the second pair of antennae. 



The second portion of the body or abdomen has but two sets of appendages^ 

 which are the second pair of legs and the caudal stylets. The second pair of legs 

 are slender and four-jointed, and are directed backward along the abdomen. 

 The caudal appendages are long and terminate in two claws. The anus opens 

 between ttiem. Of the other organs little or nothing is known. Baird was in 

 doubt whether they were hermaphrodites or one copulation sufficed to render 

 the mother and her offspring fertile for life, as in Daphnia. I have, however, 



