126 



zooLoar 



4~-^rj- 



Fig. 127.— a single facet 

 or elementary eye of 

 ttic lobster, cm, clear 

 cuticula; '«/.cr/i, nuclei 

 of cuticula ; con, cone 

 cell ; nl.con, its nuclei ; 

 nl.dsl, nuclei of outer 

 pigment cells (retina) ; 

 nlpj:, nuclei of inner 

 pigment cells; rJih, rod ; 

 7nb.ba, membrane lying 

 at base of rods; fhr.r, 

 new fibre to pigment 

 cells. G. H. Parker. 



lobster is very thick and .strong it affords 

 corresponding!}^ powerful support for the 

 well-developed musculature, for, as in the 

 grasshopper so in the lobster, the muscles 

 are attached to and pull upon the cutic- 

 ula. The powerful muscles are able to 

 make the strong strokes of the abdomen 

 used in smmming. In the abdomen the 

 dorsal muscles run longituchnally from 

 the front edge of one segment to the front 

 edge of the next. When they contract, 

 the abdomen is straightened. The ven- 

 tral muscles are verj^ complicated. They 

 run from one segment to the next and, 

 as they are attached below the hinge of 

 the segments, when they contract the 

 abdomen is bent. The musculature of 

 the appendages is well developed and 

 complicated. 



The nervous system is arranged essen- 

 tially like that of the cricket. From the 

 dorsal Ijrain two nerves pass around the 

 gullet forming the esophageal ring and 

 then pass as a pair of nerves near to the 

 ventral hne as far as the hinder opening 

 (anus) of the food canal. The two nerves 

 are tied together by ganglia in most of 

 the segments, and nerves are given off 

 to the appendages, body muscles, viscera, 

 and sense organs. 



Of the sense organs touch seems to 



