636 THE CYPEIS. 



saddle adhering to them, and looking like young beans just sprouting from the earth, 

 and carrying with them the two lobes of the seed from which they sprang. 



At fig. G is shown a very pretty little Entomostracan, belonging to a small sub-family 

 called the Sidinse. In all these beings there are six pairs of feet, the lower antennae have 

 two branches, and a row of sharp and rather strong filaments springs from the edge of 

 the larger branch. In this genus, one branch of the lower antenna? has three and the 

 other two joints. Though it is occasionally very active, passing through the water with 

 great rapidity, it is mostly dull and stationary, having a curious habit of pressing the 

 back of its head against some object, and there remaining for a considerable period 

 without moving. It derives its specific name of crystalline from its beautifully trans- 

 parent aspect. 



IN the Lynceidse there are two pairs of antennae, the upper being very short, and the 

 branches of the lower having three joints. They have five pairs of legs, and one eye, with 

 a black spot a front of it. The abdomen is jointed. All the species are rapid swimmers, 

 and their food consists of both vegetable and animal matter. 



In the Chydorus, of which one or two British species are known, the body is nearly 

 spherical, the lower antennae are very short, and the beak is very long, sharp, and curved 

 downwards. The colour is olive in the present species, and has a smooth shining 

 exterior. It may be found in ponds and ditches throughout the year. 



THE curious globular looking creature seen at fig. D is an example of another family, 

 called the Polyphemidae, having only four pairs of feet, which are not included in the 

 shield. Their single eye is very large, and has given rise to the name of Polyphemus, 

 which belonged to the one-eyed giant overcome by Ulysses and his companions. The 

 lower antennae have two branches, one with four joints and the other with three. In the 

 lower part of the carapace there is a large empty space for the accommodation of the eggs 

 and young. 



AN example of the typical genus is given at fig. E, which represents the common 

 POLYPHEMUS of our ditches and ponds. In this creature the abdomen is long and pro- 

 jects from the shell, and in the adult the eye is enormously large, seeming to occupy the 

 whole head. There is a deep notch or groove in the Polyphemus, seeming to separate 

 the body from the head. It appears always to swim upon its back, and uses both the 

 antennae and legs to drive it through the water. 



Fig. F will be described presently. 



FOLLOWING the arrangement of Dr. Baird, we now come to another section, termed 

 the Lophyropoda, or Plume-footed Entomostraca. In all these animals the mouth is well 

 supplied with teeth, and the body is enclosed in a cuirass, either covering the head and 

 thorax, or shaped like a bivalve shell, and enclosing the whole animal. There are not 

 more than five pairs of feet, only one eye, the gills are few and attached to the mouth, 

 and there are two pairs of antennae, one pair being used for locomotion. 



In the first order, called Ostracoda, a term derived from a Greek word, signifying a 

 shell, the cuirass is in two parts, and encloses the animal like a bivalve shell. The hind 

 jaws are furnished with gills. In the family of the Cypridae, the upper pair of antenna? 

 are long, have numerous joints and a pencil of long filaments ; the lower pair are short, 

 thick, and used as feet. There are two pairs of real feet. The CYPKIS, which is repre- 

 sented at fig. A, belongs to a genus which has many British species, and may be found 

 in almost every pond or ditch. The body is enclosed thoroughly in its valved cuirass, 

 something like a walnut in its shell, the fringed antennae and legs protruding from between 

 the valves and permitting the creature to move. It is a most elegant little being, the 

 shell being gracefully curved, and the antennae being fine and transparent as if they were 

 threads of glass. Dr. Baird tells us that the valves are very brittle, and that on their 

 exterior they are washed with a kind of varnish which protects them from the action of 

 the water. Owing to this varnish, these creatures cannot venture even to rise to the 



