SEA-FISHERIES LABORATORY 



311 



These appendages are peculiarly modified to act as 

 copulatory organs (see sections on Appendages and Eepro- 

 ductive System). 



The male abdomen is much more closely applied to 

 the thorax than is the case in the female. This is partly 

 due to the small number of appendages and also to the 

 very effective locking apparatus. The latter is similar 

 to that described in the female and the position of the 

 parts is the same, but the tubercles on the thoracic 

 sternum are much larger, as is also the case with the 

 concavities on the sixth abdominal somite. 



Below are given the measurements of the abdomen 

 of a male and female, both having a carapace breadth of 

 23-5 cm. 





Female. 



Male. 



No. of 











Somite. 



Greatest 



Greatest 



Greatest 



Greatest 





length. 



width. 



length. 



width. 





mm. 



mm. 



mm. 



mm. 



1 



17 



25 



17 



22 



2 



8 



22 



8 



17 



3 



7 30 



7 



23 



4 



8 



32 



8 



20 



5 



10 



35 



9 



17 



6 



20 



35 



13 



16 



Telson 



18 



21 



13 



13 



Total length, 88 mm. 



Total length, 75 mm. 



External apertures. 



The external openings are as follows : — 

 The Mouth — a median aperture on the ventral side 

 of the cephalic region between the mandibles. 



