ix, d, 4 Cowles: Palaemons of the Philippine Islands 323 



anterior border. The upper one is called the antennal spine; 

 the lower one, the hepatic spine. On each side of the rostrum 

 where it has its origin from the carapace is an eye mounted on 

 a stalk. The stalk occupies a little niche in the carapace known 

 as the orbit. Extending forward from the base of the eye 

 stalk along each side of the lower border of the rostrum is a 

 peculiar structure known as the peduncle of the first antenna. 

 Each one bears a pair of whiplike flagella. The outer flagellum 

 of the pair has a short branch arising near its origin from 

 the peduncle. Below the peduncle of the first antenna on each 

 side of the rostrum lies a large scalelike structure known as 

 the antennal scale. From the underside of each scale where it 

 has its origin from the cephalothorax arises the long whiplike 

 flagellum of the second antenna. On the lower side of the cepha- 

 lothorax are attached 5 pairs of leglike structures, which are 

 known as the first, second, third, fourth, and fifth pairs of legs. 

 The chelipeds (second pair of legs) are much larger than the 

 others, and terminate in pincers. The first legs, which are 

 much shorter and slenderer than the chelipeds, have their origin 

 from the cephalothorax in front of the origin of the chelipeds, 

 and are usually folded once under the body. They also terminate 

 in small pincers. The third, fourth, and fifth legs are slenderer 

 and shorter than the chelipeds, but stouter than the first legs. 

 They do not end in pincers. Each leg consists of jointed pieces or 

 segments. The segments of the cheliped are as follows: The 

 pincers are made up of 2 fingers, which are armed with teeth. 

 One of these is movable, and is known as the mobile finger ; the 

 other is known as the immobile finger, and is continuous with a 

 thick piece known as the palm. The immobile finger and the 

 palm are often spoken of as the propodus. The propodus, in- 

 cluding the mobile finger, is called the chela. The segment next 

 to the chela is the wrist or carpus, which is joined to another 

 segment known as the merus. Finally, the last piece or ischium 

 follows the merus and is attached to the cephalothorax by 2 

 very short pieces, the names of which it is not necessary for 

 us to consider. The first leg is made up of the same number 

 of segments as the cheliped, and these have the same names. 



The back or posterior portion of the body, which is often 

 bent under, is known as the abdomen, and is composed of 7 

 pieces, the first 6 of which are known as somites. The seventh 

 or terminal piece, which is pointed, is called the telson. Each 

 somite has a tough covering, the dorsal surface and part of 

 the lateral surface of which are known as the tergum. The 

 lower part of the lateral surface is called the pleuron. Each 



