96 



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. 'IS. Vertical and transverse section of tlie 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. 



Fig. 41. Portion of the heart showing alary muscles. 

 X 550. 



Fig. 42. Transverse section of the heart in the posterior 

 region of the oesophagus, x 420. 



Fig. 43. Transverse section of the heart, together with 

 the alary muscles ; third abdominal segment. 

 X 420. 



Fig. 44. Transverse section of the heart ; fifth 

 abdominal segment. x 420. 



Fig. 45. Transverse section across three of the longi- 

 tudinal tergal muscles. x 400. 



Fig. 40. 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. 



