38 PHYSIOLOGICAL SERIES. 



successive abdominal segments from the 2nd to the 7th. 

 Each of the anterior five innervates the segment in which 

 it lies; the 6th gives off nerves to the hinder end of tli<> 

 body. The 1st abdominal segment is supplied by the 

 metathoracic ganglion. 0. C. 1299 E. 



D. 30. A Locust (Tropidacris latreillei) dissected from the dorsal 

 aspect. The cerebral ganglion is small compared with the 

 size of the head, and is united to the suboesopha^'al 

 ganglion by relatively long connectives. The three thoracic 

 ganglia are separate, although the ineso- and metathoracic 

 show a certain amount of approximation. The metathoracic 

 ganglion is much larger than the other two ; it sends a 

 number of nerves to the anterior parts of the abdomen in 

 addition to those to the metathorax, and probably repre- 

 sents a fusion of the true metathoracic ganglion with a 

 certain number of abdominal ganglia. Within the abdomen 

 there is a chain composed of five separate ganglia situated 

 respectively in the 2nd, 4th, 6th, 7th, and 8th segments. 

 The first of them innervates the fourth segment ; tin- 

 last is larger than the others and is no doubt a compound 

 mass. 0. 0. 1299 c. 



D. 31. A female Stick-insect (Pseudobacteria ?) showing the* 

 nervous system from the dorsal aspect. The entire system 

 is of the most delicate nature and, in conformity with the 

 general structure of the insect, is greatly extended longi- 

 tudinally. The cerebral and subo3sophageal ganglia are 

 not visible. The three thoracic ganglia arc separate ; they 

 are Followed by a chain of five abdominal ganglia situated 

 respectively in the 2nd to the 6th abdominal segment-. 

 The first of these free ganglia innervates the 2nd 

 segment of the abdomen, so that presumably the first 

 primitive abdominal ganglion is included in the meta- 

 tlioracic. The terminal ganglion innervates the posterior 



jinn of the body and the -enifalia. 



The genital origin- are also shown in this specimen. 



0. C. I2!Ui. 



Muller, Nov. Act. Nat. Curios., 13d. xii. 1825, p. 568. 



