322 



The Philippine Journal of Science 



1914 



planted in the shallow water. It is in these large baclads that 

 during the months of April, May, June, July, and August, 

 especially, a local form of Palaemon carcinus Fabricius of 

 India is caught in great numbers. The fishery in this region 

 must amount to from 20,000 to 25,000 pesos per year. 



EXTERNAL CHARACTERS OF A PALAEMON 



As it is the purpose of this paper to describe the various 

 species of Philippine palaemons so that people in the Philippine 

 Islands who are not zoologists may be able to identify specimens, 

 I shall devote a little space to a simple description of the external 

 anatomy of a palaemon (fig. 1). 



Flagella of first antenna 



Cephalothorax 



Abdomen 



Antennal scale 

 Rostrum j Peduncie B V e First, tooth 



Flagellum of second antenna 



Mobile finger 



Palm 

 Fig. 1. Diagram of a palaemon 



Dactylitis 



Merits 

 Carpus Ischium 



The body of the palaemon may be divided into a forward or 

 anterior part known as the cephalothorax and a hind or poste- 

 rior jointed part known as the abdomen. The cephalothorax is 

 composed of a head and a thorax which are so closely joined 

 together that there is no neck, and it is covered above — dorsally — 

 and on the side — laterally — by a tough shield-shaped carapace. 

 From the front of the carapace a pointed beak or rostrum ex- 

 tends forward, and is armed with teeth along its dorsal and 

 its lower — ventral — border. The "first tooth" in the following 

 description means the most posterior tooth arising from the 

 carapace and the number of teeth on the dorsal and ventral 

 borders of the rostrum is indicated in the form of a fraction 



which I have called the rostral or dental formula /1°> H> 12,13 \ 



\ 3, 4 /• 



There are 2 spines on each side of the carapace near the 



