1894.] certain External Parts o/Palaamon serratus. 235 



I. Length of body from tip of rostrum to end of telson (exclud- 

 ing terminal spines). 



II. From hindermost point of orbit to hinder edge of carapace 

 in a straight line. 



III. From tip of rostrum to median point of hinder edge of cara- 



pace. 



IV. From tip of rostrum to tip of first dorsal spine. 



V. From tip of rostrum to tip of last (hindermost) dorsal 



spine. 



VI. From tip of first to tip of last dorsal spine. 

 VII. From tip of last dorsal spine to tip of the last but one. 

 VIII. From tip of last dorsal spine to median point of hinder 



edge of carapace (post-spinous portion of carapace). 

 IXa. The right squame from tip of tooth to posterior edge of the- 



external articular tubercle. 



IX&. The left squame measured in like manner. 

 X. The anterior and posterior median points of the 1st abdomi- 

 nal tergum. 

 XI. Posterior portion of the 1st abdominal tergum measured in 



like manner. 



XII. The 2nd abdominal tergum measured in like manner. 

 XIII. The 3rd 



. XIV. The 4th 

 XV. The 5th 

 XVI. The 6th 



XVII. The telson from the median point of the anterior edge to- 

 the tip of the median posterior projecting tooth (i.e., ex- 

 cluding the terminal spines). 



XVIIIa. Exopodite of the 6th abdominal right appendage from the 

 tip of the dorsal or fixed tooth to the posterior edge of the 

 dorsal articular tubercle. 

 XV1II6. Exopodite of the 6th abdominal left appendage measured in 



like manner. 



XlXa. From base of lateral spine projecting from the posterior end 

 of the telson to the base of the posterior spine on the- 

 dorsal surface of the telson on the right side. 

 XIX6. Similar measurement for the left side. 



Measurements I to III were made with compasses, and may be re- 

 garded as accurate to within about 0*5 mm., except No. I, the body 

 length, which is somewhat less accurate. The remaining measure- 

 ments were made under a microscope, and are accurate to within 

 0-05 mm. 



For the purpose of comparison the measurements are all expressed 

 in terms of the body length, which is taken as = 1000. 



