448 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



groove on the anterior aspect of the ventral 

 tube. x 45. 



Fig. 37. Section of the mid- ventral region of the meso- 

 thorax showing the relations of the nervous 

 system, medifurca and the ventral groove, 

 x 200. 



Fig. 38. Vertical and transverse section of the ventral 

 tube. x 180. 



Fig. 39. Portion of the heart showing the non-striated 

 circular muscle bands. x 550. 



Fig. 40. Vertical and longitudinal section of a chamber 

 of the heart, x 550. 



Portion of the heart showing alary muscles, 

 x 550. 



Transverse section of the heart in the posterior 

 region of the oesophagus. x 420. 



Transverse section of the heart, together with 

 the alary muscles ; third abdominal segment. 

 x 420. 



Transverse section of the heart ; fifth 

 abdominal segment. x 420. 



Transverse section across three of the longi- 

 tudinal tergal muscles. x 400. 



Longitudinal section through the first and 

 second thoracic ganglia, taken slightly to the 

 left side to show the median accessory nerve, 

 x 150. 

 Fig. 47. Longitudinal section through the meta- 

 thoracico— abdominal ganglion. x 320. 



Fig. 48. Semi-diagrammatic reconstruction of the 

 nervous system of Anurida. x circa 100. 



Fig. 



41. 



Fig. 



42. 



Fig. 



43. 



Fig. 



44. 



Fig. 



45. 



Fig. 



46. 



