PALINURUS OR THE SPINY LOBSTER OF BOMBAY. 373 



see two small pointed processes of the mandible meeting in the 

 middle line and articulating with the epistoma by a membrane 

 throughout their whole length. On the outer hinder portion of the 

 mandible, diagonally opposite the pointed process, you find a large 

 pointed peg. which fits into a corresponding socket at the base of the 

 apimeron which is here specially strengthened and calcified. On 

 examining the endoskeleton you will find this point specially sup- 

 ported by stout transverse stays or apodemes, reaching from side to 

 side of the cephalo-thoracic cavity. 



On the diagonal line joining this pivot with the anterior pointed 

 process the mandible rotates. 



The whole of this large rounded piece is the coxopodite. Close to 

 the origin of the anterior tooth-like process is a three-jointed palp. 

 The proximal segment represents the basipodite, the distal two, the 

 endopodite. This we learn from a comparative study of certain lower 

 Crustaceae, in whom we find the basal joint of the palp bearing both 

 endopodite and exopodite. In the dried skeleton the calcified tendons 

 of the adducter muscles remain attached to the mandibles. 



We have already seen a small portion of the ventral surface of the 

 epistome. In front it is reflected back dorsally on itself so that the 

 whole is a flattened cone which forms part of the anterior wall of 

 the head. The epistome is homologically the sternum of the anten- 

 nary somite, but in this case owing to its reflexion it forms part of the 

 dorsal surface of the head. 



To understand the structure of the antenna, you should compare 

 it with that of the Prawn or the Cray-fish. In these latter 

 animals you at once recognise the homologue of the protopodite 

 (here called the protocerhe from the Greek keras, a horn or feeler), 

 with a short coxorerite, on the ventral surface of which is a small 

 nipple-like projection perforated by an opening. This opening you 

 find on dissection leads into the duct of the kidney or "green gland." 

 Then you have an obvious basicerke, to which are articulated an 

 exocerite in the form of a scale or flat plate, very large indeed in the 

 Prawn. You will readily recognise in the rest of the long feeler an 

 endocerite with two large basal segments, and a long annulated 

 terminal portion or flaydlum (Latin, a whip). 



In Palinurus you find no trace of the exocerite. You find a very 

 long annulated feeler, sometimes a yard long, with apparently 



