2 2 COMPARATIVE ANATOMY 



only the first pair are pouches communicating with the cavity 

 of the gut : the two posterior pairs are thickenings of the 



Fig. 4 



Lumbricus hcrculcus. A. A view of the organs contained in the first twenty-two 

 somites, a";; seen when the animal is opened by a longitudinal dorsal incision, and 

 the body walls are pinned out without cutting the septa. The pins are placed in the 

 3rd, 9th, and iSth somites. B. View of the first sixteen somites of the same worm 

 after removal of the alimentary tract, to show the nervous system and reproductive 

 organs, be, buccal cavity, cut across ; eg, cerebral ganglia ; g, gizzard ; int, 

 intestine ; «//i, nephridia ; od, oviduct ; oe, oesophagus ; 07'^ ovary in somite 13 ; 

 //;, pharynx with radiating muscular strands; prv^ proventriculus ; j, septa; 

 sd, sperm duct; sf, seminal funnels; spth^ spermathecas in somites 9 and 10; 

 sp.s^ sperm sacs ; /, testis. 



cesophageal wall, which is here hollowed out by a number 

 of cavities ending blindly behind but opening into the first 



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